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    Walkthrough by daveb

    Version: 1.0 | Updated: 11/08/17 | Search Guide | Bookmark Guide

                                   Doom 4 Walkthrough
    
       Version 1.0.
    
                              Acknowledgements and Caveats
    
       Thanks, id Software for making such a great game!
    
       Also, watching zomeister's Pistol-Only walkthrough helped me with several
       strategy points. So props to that individual: please watch the madness if
       you want to be inspired: https://www.youtube.com/watch?v=AyVVc0FcS4E
    
       Caveats: I have not read the "Official" Guide by Prima Guides at this
       point. I may do so soon and amend this guide, as time permits.
    
                            Introduction and Game Mechanics
    
    Overview
    
       Welcome to Doom 4, an intense and sensory First Person Shooter!
    
       The game is set mostly in a large energy facility on Mars, with occasional
       forays into Hell!
    
       The game is heavy on action and fighting, and it keeps its cut-scenes
       short and punchy.
    
       The visuals are impressive, contrasting space-tech with organic demons.
       They are also pretty gory: potential noghtmare fodder for kids. Even
       though you will plow your way through hundreds of monsters in these
       missions, at least none were human at the time of death.
    
    Basic Plot Summary
    
       You awaken to being chained to a bed, and quickly assume the hero's role:
       combatting an experiment with Hell gone awry. Over the missions, you'll
       see that cutting-edge research into new energy sources degenerated into
       cultish madness, including ritualistic sacrifices. It's up to you to stop
       the unleashed demons.
    
    Controls
    
          PS 4           X-Box       Description                                 
           L1             LB         Use equipment (usually Grenade)             
           L2             LT         Weapon Modifier (meaning depends on weapon) 
           R1             RB         Switch or Select Weapon                     
           R2             RT         Fire Weapon                                 
           R3      Press Right Stick Melee Attack / Glory Kill                   
         Square            X         Chainsaw                                    
        Triangle           Y         BFG                                         
         Circle            B         Crouch / Stand (toggle)                     
            X              A         Jump                                        
        Up Arrow        DPad Up      Swap Weapon Mod                             
       Left Arrow      DPad Left     Previous Equipment                          
       Right Arrow    DPad Right     Next Equipment                              
       Down Arrow      DPad Down     Mission Objective Summary                   
    
    Weapons
    
      Pistol
    
       What the Pistol lacks in power it makes up for by having unlimited ammo.
    
       The lack of power can be an advantage if you are trying to stun a demon in
       order to Glory Kill it, if you are trying to extract more stuff from the
       kill.
    
       My upgrade strategy: save the upgrades for the end, or maybe induldge in
       the first 1 point upgrade. There are more important ways to spend one's
       upgrade points.
    
      Shotgun (available Mission 0)
    
       Although the shotgun is eclipsed by the Super Shotgun (which is much
       better, once upgraded), you'll have no real choice for the first few
       missions. Because of this, it isn't really worth putting Weapon Upgrade
       points into the shotgun, at least not until later in the game if you are
       trying to get 100%.
    
       When you get to the first Field Drone, the Shotgun is the only weapon you
       have to modify, so you have to get a mod at this early point: go for
       Explosive Shot, which is easier to use to get the "Twofer" Challenge (for
       Mission 2).
    
       Cyber-Mancubi count as Mancubi for the Changed Shot Upgrade Challenge.
    
       (Technically, the game refers to this weapon as the "Combat Shotgun", but
       nobody calls it that.)
    
      Plasma Gun (available Mission 2)
    
       Although it's individual shots are rather weak, it fires quite rapidly.
    
       More importantly, Heat Blast is a really powerful Weapon Modification.
       Basically, it allows you to kill everything near you at the same time
       without using ammo, BUT it requires you to shoot the gun to charge up the
       blast. There are 2-4 places you can use the Heat Blast and Quad Damage
       Powerup to really plow through large numbers of demons.
    
       I haven't found the Stun modification to be very useful: it wastes ammo,
       it's hard to stun more than 2 demons, they don't stay stunned long, and
       you still have to kill them (taking both time and ammo usually).
    
      Assault Rifle (available Mission 2)
    
       Each individual shot from the Assault Rifle is rather weak and becomes
       weaker and harder to hit from a difference. Few demons can be killed with
       a single shot; expect a cacodaemoon (etc) to take 30+ shots even up close.
    
       The Tactical Scope changes things a bit: it makes the thing pretty
       effective for sniping, and the upgrades make it pretty damaging. Even so,
       it's a bit tedious killing things with this weapon.
       However, it makes for a nice change, since the opportunities for sniping
       are few in this game. You can usually get the challenge upgrade naturally
       over the course of the game, but you can also replay an earlier mission to
       get it pretty easily.
    
       The Mini-Missiles seems like a cool upgrade but they aren't that powerful
       or predictable. One nice use is for dealing with multiple Lost Souls. Most
       other monsters are too strong for this to be an elegant attack.
    
      Super Shotgun (available Mission 4)
    
       A weapon big enough that it'll at least distract anything. Fully upgraded,
       it's my weapon of choice for Hell Knights, or combats with a long chain of
       individual demos.
    
       The challenge upgrade can be a bit difficult: I usually get very close to
       one demon and shoot through it to get to another one close behind; this
       seems easier than lining them up side-to-side.
    
      Chain Gun (available Mission 6)
    
       A powerful weapon that is a bit annoying to use because it takes a a few
       seconds to start up.
    
       The Gattling Rotator works, but you have to hold down the modifications
       button the entire time: I don't really like that.
    
       The Mobile Turret mod is a great way to deliver a lot of damage. I usually
       try to fully upgrade this modification since it's useful against bosses.
    
      Gauss Cannon (available Mission 5)
    
       The most powerful standard weapon, even without mods. Siege Mode is the
       most powerful mod (by far), and it is strongly recommended. Its challenge
       upgrade is easy too.
    
       The Precision Bolt mod is also pretty good but it's a lot harder to fully
       upgrade and only kills once thing at a time, so I seldom use it.
    
      BFG (available Mission 8)
    
       The Big F-ing Gun. This will clear out a whole room of demons, but it can
       be a little unpredictable in how it works.
    
       Ammo is found individually, and you always have a limit of 3. However, the
       Ammo Boost II rune WILL cause enemies to randomly drop BFG ammo when they
       die so there isn't too much of a shortage.
    
      Chainsaw (available Mission 2)
    
       This crazy melee weapon will definitely kill any monster in range that you
       have enough fuel to kill. The initial capacity is 3 Fuel Units, which is
       the amount in every gas can. Each Argent Cell upgrade to the Ammo Capacity
       increases your capacity by 1 Fuel. So fully upgraded, you have a capacity
       of 7 Fuel Units.
    
       Killing with a chainsaw is considered a Glory Kill that'll dump a huge
       pile of ammo.
    
       Fuel to kill various demons:
    
         * Imp: 1
         * The Possessed: 1
         * Unwilling: 1
         * Possessed Guard: 1
         * Possessed Securities: 1
         * Hell Razer: 1
         * Hell Knight: 3
         * Summoner: 3
         * Cacodaemon: 3
         * Pinkie: 3
         * Spectre: 3
         * Revenant: 3
         * Mancubus: 5
         * Cyber-Mancubus: 5
         * Hell Baron: 5
    
    Monsters
    
      The Possessed, Unwilling
    
       These idiots simply stagger around, vaguely coming toward you.
    
       In Nightmare mode, they do quite a bit of damage; in easier modes they are
       merely pesky.
    
      Imps
    
       Monkeys with fireballs with great aim. You have to move constantly and
       keep a lookout to avoid getting hit.
    
       They can take a fairly large amount of damage when they are climbing
       around on vertical surfaces.
    
       For players in Nightmare mode, Imps will probably cause more deaths than
       any other demon.
    
    Possessed Engineers
    
       Somewhat like the Possessed, except they explode when they die, and they
       charge at you to cause trouble.
    
       These guys are walking bombs - typically when they die they'll fly away
       from you which mitigates the problems. But some weapons might cause them
       to fly at you, and they'll do moderate damage.
    
       Even if you jump from above them and Glory Kill them, it does not count as
       a Death From Above Glory Kill (at least for the purposes of Rune or Combat
       Challenges). I'm assuming they their firey plume keeps them safe ? TODO:
       read the damn codex on this
    
      Possessed Soldiers and Possessed Securities
    
       These two monsters differ in that the latter has shields.
    
       They have 3 attacks:
    
         * Plasma Volley: an attack of many straight-moving weak plasma baubles
         * Plasma Grenade: a stronger attack, similar to the Rocket Launcher /
           Remote Detonation. It expands before blowing up like a bomb.
         * Melee Attack: these are fairly weak for Possessed Soldiers, but they
           are quite strong from the shielded soldiers
    
       The shields are a big difficulty: the Gauss Cannon or Chainsaw are the
       surest ways to kill them - you'll run into them before you have the Gauss
       Cannon. Otherwise, try running around them (around a structure) or jumping
       over them. Also they have to put their shields down when the jump/drop.
    
      Hell Razers
    
       These hellions attack with a laser in their arm, or a melee attack.
    
       They have a lot of hit-points, but they aren't too hard to kill.
    
      Lost Souls
    
       These little punks are very damaging.
    
       It's best to snipe them from afar (effective weapons: Assault
       Rifle/Tacticle Scope, Rocket Launcher/Lock-On, BFG). At the last moment
       when they are swooping in on you, the Shotgun or Super-Shotgun is probably
       the best, if you're quick.
    
       They can make little turns, but you can sneak behind pillars or protected
       areas.
    
      Hell Knights
    
       These are brutal melee attackers.
    
       They will jump toward to very fast.
    
       It is best to approach them right after an attack (Super Shotgun, Gauss
       Cannon) then back-off - a kind-of dance, or just use the Chainsaw which'll
       definitely kill them if you have fuel.
    
      Summoners
    
       These red-dressed ladies fire intense energy beams along the floor.
       Fortunately, the shot come with a pre-shot, so if you see a short red
       flame running along the ground, get away from it.
    
       The Rocket Launcher / Lock-On's Multi-Target Upgrade requires 5 kills on
       Summoners, so if you want to get that upgrade, you'll want to kill every
       summoner with lock-on rockets. That said, this upgrade isn't particularly
       useful.
    
      Cacodemons
    
       Big floating eyeballs with gigantic purple missiles.
    
       They do (as a hint notes) have a weak point near their eye opening, and
       precision shots with the tactical shot of the assault rifle can kill it
       from afar pretty quickly.
    
      Pinkies and Spectres
    
       These are big charging idiot monsters. The Pinkies are substantially
       heartier. They are literally pink. The Spectres are essentially camoflaged
       Pinkies. They blend into their surroundings.
    
       I suggest using Super Shotgun, Chainsaw, Gauss Cannon on these guys. But
       really, any weapon will work.
    
       Their tail/backside is their weakness. A single well-aimed up-close Super
       Shotgun blast to the base of the tail will usually kill it. (Two such
       shots definitely will, but most of the time the Pinky will start moving
       before you can get a second shot)
    
      Mancubi and Cyber-Mancubi
    
       These large (obese) demons shoot damaging fireballs. The Cyber-Mancubi are
       somewhat more annoying because their shots leave a toxic (green) residue
       that you must avoid (it only lasts a few seconds).
    
      Hell Barons
    
       These are like Hell Knights except that they can shoot missiles. With
       horns.
    
       They are really not that tough, because they can be taken down by 2 Gauss
       Cannon / Siege Mode shots.
    
    Equipment
    
       Generally speaking, most players use mostly one type of Equipment: the
       Frag Grenade. It is effective, you get it early on, and it is easy to
       understand.
    
       The Siphon Grenade is substantially harder to aim, and less damaging, so
       it isn't used too much.
    
       The Hologram (sometimes called the Decoy) seems like a good idea, but I
       really haven't found places I personally like to use it.
    
       Contact me if you have suggestions for Siphon Grenades or Holograms!
    
      Frag Grenades
    
       These have both good radius and damage and are recommended. I know that as
       a beginner, I under-used them. One problem is that they take a long time
       to regenerate until you get the first Praetor Suit Equipment Upgrade.
    
      Siphon Grenades
    
       These pull energy from demons in their radius and give it to you. But the
       amount transferred isn't that great, so it tends to be overlooked.
    
    Level Overview
    
       Mission                Subtitle   Elite  Argent Field  Rune   Secrets Data 
                                         Guards Cells  Drones Trials         Logs 
       Mission 1: The UAC     Rip and    1      0      1      0      3       2    
                              Tear       
       Mission 2: Resource    Know Your  3      0      1      0      8       2    
       Operations             Enemy      
       Mission 3: Foundry     Meltdown   3      0      1      0      6       3    
       Mission 4: Argent      Beginning  4      1      2      2      5       4    
       Facility               of the End 
       Mission 5: Argent      Argent     3      2      1      2      7       4    
       Energy Tower           Tower      
       Mission 6: Kadingir    Into the   4      1      1      2      6       7    
       Sanctum                Fire       
       Mission 7: Argent      Hell on    4      1      1      2      6       5    
       Facility (Destroyed)   Mars       
       Mission 8: Advanced    A Brighter 3      2      1      2      10      4    
       Resource Complex       Tomorrow   
       Mission 9: Lazarus     Lazarus    4      1      1      2      9       5    
       Labs                   
       Mission 10: Titan's    Titan's    2      1      1      2      6       4    
       Realm                  Realm      
       Mission 11: The        The        2      1      1      2      3       3    
       Necropolis             Crucible   
       Mission 12: VEGA       I am VEGA  3      0      0      0      5       4    
       Central Processing     
       Mission 13: Argent     The Well   0      0      0      0      5       0    
       D'Nur                  
    
    Weapon Upgrade Tokens
    
       You spend these to improve your weapons:
    
       Weapon         Upgrades                     Upgrade Points Required For    
                                                   All Mods                       
       Assault Right  Tactical Scope, Mini         18                             
                      Missiles                     
       Combat Shotgun Charged Shot, Explosive Shot 18                             
       Plasma Rifle   Heat Blast, Stun Gun         18                             
       Chain Gun      Gattling Revolver, Mobile    18                             
                      Turret                       
       Super Shotgun  -                            9                              
       Pistol         -                            9                              
       ---            ---                          ---                            
       Total                                       108                            
    
       You earn Weapon Upgrade Tokens as follows:
    
       Type                Missions Earned per Mission Total 
       Secrets/Exploration 1-13     2                  26    
       Challenges          2-13     3                  36    
       Combat              3-13     5                  55    
       Boss Fights         9,11,13  1                  3     
       unknown             ???      ???                4     
       ---                 ---      ---                ---   
       Total                                           124   
    
       So, if you 100% the game you should have 124 - 108 = 16 unusable Weapon
       Upgrade points at the end. Another way to look at it: there are 16 extra
       Weapon Upgrades Points.
    
       That said, the extra combat upgrades have to be earnedd, so earning 100%
       on one playthough (ie without taking advantage of Mission Replay or
       dying), is logistically tricky, if not impossible.
    
    Checkpoints
    
       Checkpoints save your ammo, health and armor levels, as well as the
       locations of pickups of the same nature.
    
       On the other hand, Secrets, Argent Cells, and Elite Guards are all saved
       without making a checkpoint.
    
       This system usually works quite well, but the Argent Cells have a
       side-effect of filling up whatever power you upgrade. This isn't saved
       unless you find a checkpoint elsewhere. This rarely comes up besides in
       Mission 7 where we provide some advice.
    
    Your Dossier
    
       These are accessed by the central button on PS4.
    
       These pages are introduced pretty well described by in-game tutorials, so
       I'm not going to repeat all that information.
    
         * When you get an Auto-Map, the effect is to enhance the map in your
           Dossier. Praetor Suit upgrades can improve the map in various ways
         * Weapons and Praetor Suit Upgrades are explained over the first few
           Missions
         * Tutorial Codex pages are automatically added to the Codex page.
         * The Codex page will let you see if you have missed any Codex Entries
    
    Navigation
    
       Your dossier has a 3-d map that is pretty nice, but it doesn't give a
       coordinate system, nor labels for places, nor even a reference direction,
       like North. It does provide some icons that can be used as landmarks.
    
       Fortunately, almost every location in this game looks somewhat different,
       so it's not so bad. But pay attention to the names given to certain major
       rooms/locations, since usually if i give it a name, then you'll arrive
       there a few times.
    
    Difficulty Levels
    
       Based on my own experience (and I could be wrong):
    
         * difficulty levels affect:
              * damage done by demons
              * gains from ammo, armor, and healh pickups
              * runes: Rich Get Richer
         * difficulty levels do not affect:
              * number or placement of demons
              * chainsaw
              * secrets (except the size of an Armor pickup)
              * runes: In-Flight Mobility
         * i'm not sure if these are affected:
              * health of monsters
              * damage of user's weapons
              * environmental damage to the user
              * environmental damage to the demons
    
       Difficulty level     Max Imp Fireball Damage Small Armor Pickup 
       Please Don't Hurt Me ...                     5                  
       Hurt Me Plenty       ...                     ...                
       Ultra-Violence       ...                     ...                
       Nightmare            ...                     1                  
    
       Ultra-Nightmare is the same as Nightmare for this information.
    
    Runes
    
       I provide hints about how to complete the Runes Challenges where you come
       across them. These are hints about when to use runes, and how to upgrade
       them (as easily as possible- both on a single playthrough as well as using
       Mission Replay).
    
      Vacuum
    
       Easy to get and the most important rune. Upgrading is easy as well - jump
       make sure to remember to equip it after you complete the challenge (it
       won't remind you in nightmare mode).
    
      Dazed and Confused
    
       This rune comes in handy for the Bosses at the end of Mission 11, and for
       fulfulling the Combat Challenge "To Be Knighted" for Mission 4: without
       the Jump Boots, Death From Above Glory Kills on Hell Knights can require
       some setup.
    
      Ammo Boost
    
      Equipment Power
    
      Savagery
    
      ...
    
      In-Flight Mobility
    
      ...
    
      Armored Offensive
    
                                    Using this Guide
    
       Secrets, Field Drones, Argent Cells, Rune Challenges are all written in
       uppercase at their secret location, with dotted notation where the first
       number is the mission and the secret is the index of the location in the
       Dossier Overview/Map page. For example, SECRET 14.3 would be the third
       secret in the dossier in mission 14 (but there's really only 13 missions).
       This is intended to facilitate searching.
    
       As a perhaps dubious consistency I will use all-caps the first time you
       meet a monster or can collect a weapon. Subsequently, I will use title
       case.
    
       (In the case of monsters, there are two grammatically annoying ones: The
       Possessed and Possessed Security. I'm just going use them like they were
       real nouns, and i'll therefore pluralize them as The Possesseds and
       Possessed Securities.)
    
       I will use title case (ie first letters capitalized) for various other
       collectibles: Suit of Armor, Small Armor, Health Station, Mega-Health,
       etc.
    
       Similarly CHECKPOINT is always written uppercase to indicate that the game
       will give a checkpoint. The significance of that is that it is nice to
       load up on supplies right before getting the checkpoint. (So that if you
       die, you won't have to get the supplies again)
    
                                    About this Guide
    
       This is the first Walkthrough I have written. I hope you find it useful.
    
       I am no expert game player. I just really like this game, and decided to
       write a walkthrough since the one like I wanted didn't exist.
    
       I found it to be an interesting challenge, mostly due to the difficulty of
       describing locations.
    
       I welcome contributions, compliments, suggestions, errata, strategies,
       complaints, and donations. Contact me via github for details, or submit
       bug reports:
    
         https://github.com/davebenson/doom4-walkthrough
    
                                   Mission 0: Pre-UAC
    
       At the beginning of the game, you wake up chained to an operating table.
       As you break out of your bonds, four demons surround you, your first
       encounter with THE POSSESSED.
    
       Before you have control, you kill one by hand, and grab a pistol.
    
       Shoot the remaining three.
    
       Interact with the screen (to the right of the door) and proceed into the
       central room with the Praetor Suit. Interact with it, and meet Dr Hayden.
    
    Mission 0: Fight: Glory Kill Tutorial
    
       You will come upon a staggered The Possessed. After killing it, kill the
       remaining 4 weaklings.
    
    Mission 0: Meet the Imp
    
       Interact with a corpse to get the SHOTGUN.
    
       Enter the next room.
    
       A quick cut-scene will play as the IMP scurries down from the rafters.
       Kill it, obviously (using the Shotgun).
    
    Mission 0: Fight: Blue Elevator Chamber
    
       You exit the anteroom to see 8? The Possessed worshipping an Orb. You can
       Glory Kill them if you need health or kill them en masse by shooting the
       barrel.
    
       After destroying the Orb, about 15? Imps will gradually materialize. Keep
       moving! There are two sheltered areas: the entrance area, and a
       control-room overlooking the main chamber.
    
       Grab all stray stuff before entering the elevator. CHECKPOINT.
    
                           Mission 1: The UAC "Rip and Tear"
    
    Mission 1: Intro
    
       The mission starts with you exiting an elevator, and dropping onto a lower
       plane. 3 small armor pieces are there; proceed upward to find CODEX ENTRY
       "Environments / The UAC".
    
       As you approach another tall cliff, you can see Imps running off into the
       horizon: these can be shot but it's not worth the effort. You can also
       shoot The Possesseds below, but it's better to use them as walking health
       bonuses.
    
    Mission 1: Fight: Pre-Blue-Keycard
    
       This is the first real fight of the game. It occurs on a 2-level
       dual-figure-eight structure.
    
       Like many fights throughout the game, you will learn your own opening
       gambit. For me, I target the 2 POSSESSED SOLDIERS that appear right in
       front of you: one in the center in front of a pinnacle, and one near a
       barrel that can be shot. After that, just keep moving and shooting.
    
       You'll be able to recharge over the next easy fight, so use up all the
       health and armor during the fight.
    
    Mission 1: Keycard and Secret
    
       After the demonic threat is neutralized, a gate opens up, opposite the
       entrance location. However, another gate immediately (requiring the Blue
       Keycard) blocks progress. Turn right and walk down a tunnel. Behind a
       large block is a corpse with a Blue Keycard.
    
       After getting the keycard, stand on the block and look around for a tunnel
       above you. You should jump to it, and pick up SECRET 1.1 and your first
       collectible, COLLECTIBLE 1.1 "Combat Shotgun Model, Blueguy".
    
       Continuing through the tunnel, you'll get to the gate, which will open.
    
       You'll get some ammo, but more importantly, the FRAG GRENADE, which is
       very useful, especially once your suit's equipment upgrades are done.
    
    Mission 1: Fight: Stray Possessed and Imps
    
       There's about 6 The Possesseds and 3 Imps.
    
       After killing those guys, enter the cave to the right (at the top of the
       incline). You will find some worshipping Possessed and an Auto-map.
       Continue out the cave to find a Praetor Token (ELITE GUARD 1.1) on the
       right before jumping down.
    
    Mission 1: Fight: Stray Imps
    
       As you drop down the last level of this spit of land, 5 Imps will attack
       from various directions.
    
       CHECKPOINT.
    
       After that, look for the large tank with TRI 9-C printed on it, and enter
       its lower level. There is a lever through that you should interact with
       then enter the Classic Doom Level. Exit the structure and you should be
       able to see up the path to SECRET 1.2, CLASSIC MAP 1.1 "Doom II:
       Entryway".
    
    Mission 1: Fight: Classic Doom Level
    
       There are 4 Possessed Soldiers standing on pedestals in here. I usually
       use a Frag Grenade to kill the left one, then snipe the right one from
       just under the pillar. The remaining two can be taken out one-at-a-time.
    
       If you actuate the switch nearer the entrance, you can get some minor
       booty. Mostly, this fight isn't worth the effort.
    
       After this, jump onto the crates at the end of the landing bay, and jump
       the chasm.
    
       At the end of this area, you may catch a glance of the Field Drone flying
       away to the right. But go left to an area with Health and Armor, and the
       second CODEX ENTRY "Environments / The UAC".
    
    Mission 1: Fight: Just Across the Chasm
    
       Go back, and to the right where you saw the Field Drone; it's floating
       right ahead. Interact with it: I tend to get Explosive Shot as it makes an
       upcoming challenge easier, but it isn't necessary.
    
       You will come across some The Possesseds worshipping a corpse. There are 3
       Possessed Soldiers around in the peripheries as well, and they will be
       join in the fun by some Imps that'll spawn, potentially close to you.
    
       After killing them, CHECKPOINT.
    
    Mission 1: Fight: Pre Entranceway Area
    
       This canyon can be approached in two ways:
    
         * go directly up the canyon
         * back up and ascend some cliffs to the left (there's a Medium Health
           visible), cross over the canyon on a land bridge, then turn left and
           climb up a yellow metal wall.
    
       Either way, expect 5+ Imps (plus some The Possesseds).
    
       CHECKPOINT.
    
       You should see a suit of Armor on a small plateau. Just before that, at
       the canyon's bottom, look around for a small backfacing greenlit "secret"
       tunnel. It leads to a cliff with SECRET 1.3 to COLLECTIBLE 1.2 "Imp Model,
       Classicguy".
    
    Mission 1: Fight: Entrance
    
       You can approach this fight up the main road (over the plateau with a suit
       of armor), or from the side using the plateau to the right. Use grenades
       to knock these forces back, and retreat to snipe at the various demons.
    
       It's about 6? Possessed Soldier, 6? Imps, and 12? The Possessed.
    
       Search all over for ammo.
    
       Now, go up to the top level. You'll see a medium Health. And at the end of
       both of the broken tracks there are carts containing Health and Ammo.
    
       Enter into either of the twin doors, there's some armor - pick it up if
       needed, then proceed to the waypoint.
    
                    Mission 2: Resource Operations "Know Your Enemy"
    
    Mission 2: Notes on Combat Challenges
    
         * Two-fer: This is easy with the Explosive Shot: use the Weapons Mod key
           and shoot a Possessed that is in close range of another Possessed. Or
           stagger one in order to line them up carefully. It can be done without
           weapon mods by staggering two Possessed and getting really close to
           one and shooting through it to the other staggered being.
         * Variety is the Spice of Death I: perform 5 different Glory Kills on
           the Possessed. There's a lot of options; use the Pistol (instead of
           Shotgun) to more reliably stagger (as opposed to kill) them.
         * Quite the Explorer: Find 3 Secrets. This should be pretty easy, with
           this guide.
    
    Mission 2: Fight: Tiny fight before opening hatch
    
       5 Possessed wait here, and 2 Imps spawn quickly. Kill the Imps and use the
       Possesseds to work on either Challenge "Variety is the Spice of Death I"
       or "Twofer" (this is easiest using the Explosive Shot modification).
    
       You can't open the hatch yet: "Low Power". Instead, open a door to find a
       number of The Possessed, and keep going to an Imp at the top of the
       stairs. "Reset Power" (by interacting with a screen), to watch a bit of a
       cut-scene featuring an Olivia Pierce recording.
    
       Looking down at the stairs from the top, you should see a platform at your
       level with a blood smear on the back wall: a standard marker for a secret
       in this game. Go there, and look for some ducts to climb through. You'll
       get to SECRET 2.1 and a suit of armor.
    
       Back at the bottom of those steps, find an Auto-Map: use it.
    
       Continue to the waypoint and an Open the Maintenance Bay Door.
    
    Mission 2: Fight: Tiny fight in catwalk area with Original Doom Level
    
       Some Possessed are followed by 3 Imps. Go where they originated onto a
       crane-like catwalk. Jump over its left railing, and look for a platform
       somewhat above you: jump to it. Look for the Lever and pull it.
    
       Jump back down, keeping an eye out for some Imps that'll spawn right
       around you. You should see the SECRET 2.8, CLASSIC MAP 2.1 "Doom - Hangar"
       up a small staircase with some Health and Shotgun ammo.
    
       After that, open the door with the waypoint to meet the Possessed
       Engineer. Shoot him and he'll fly back, killing the numerous Possesseds in
       the background.
    
       A battle awaits after opening the next door.
    
    Mission 2: Fight: U-shaped catwalk area
    
       This can be a difficult fight, but judicious use of Grenades, Barrels, and
       Possessed Engineers can make it fairly painless.
    
       Post Fight: There's CODEX ENTRY "Environments / Resource Operations" and a
       door.
    
       You can enter the room through a path with more goodies by looking for a
       screen in the left of the control console that you can interact to "???".
       This will stop the fast moving elevators at the central part of the U.
       Climb up the elevators and enter through the second story for health,
       armor, and shotgun ammo.
    
       No matter which way you go, you'll be in a locker room with some Shotgun
       Ammo, the Chainsaw, and a Health Station.
    
    Mission 2: Fight: Industrial Train Depot
    
       A long hallway fight, with a bit of a side-corridor at the end.
    
       You can fight it from the entrance gate, or you can charge in. It doesn't
       really make much difference.
    
       ??? CHECKPOINT.
    
    Mission 2: Getting the yellow keycard
    
       Cross the train-tracks on the far-side of the room from your entrance. You
       will see a gas canister across the tracks. Turn left and carefully go
       through the hatch which automatically opens and closes. It is an elevator.
       When the door opens on the upper level, there should be a large armor.
       Take it and go forward. There should be a train on the left leading back
       to the Industrial Train Depot, and on the right is a Security Station.
    
       Drop drop and take out the few The Possesseds.
    
    Mission 2: Fight: Tiny fight in front of Security Station
    
       A few The Possesseds.
    
       Since you don't have the Yellow Keycard yet, you will have to go down the
       hall to a developed outdoor area.
    
    Mission 2: Fight: Developed Outdoor Gore Nest
    
       Before destroying the gore nest, take out the 6? The Possesseds possibly
       using Glory Kills to get more health. I tend to use the pistol to save
       ammo.
    
       After destroying the Gore Nest, a large number of Imps and Possessed
       Soldiers appear, keep moving and shoot the barrels to kill some of them
       while saving ammo. Make note of the two supply caches containing
       ammo+health before starting.
    
       Hint: The chainsaw is useful here to kill 3 demons and get lots of ammo.
    
    Mission 2: Getting the yellow keycard (continued)
    
       On the lower level, Call the Elevator and see a replayed cut-scene of the
       demon carrying the Yellow Keycard guard. Enter the elevator and press the
       button.
    
       On a catwalk area you'll find some health, FIELD DRONE 2.1, shotgun ammo
       and the corpse of the Yellow Keycard guard. I recommend waiting to use the
       field drone until you have the Plasma Rifle. Take the Yellow Keycard and
       watch out!
    
       Go through the hatch then drop down into the Industrial Train Depot, right
       in front of a Yellow Keycard Door.
    
       But, don't go there yet! Instead, retrace your earlier steps to the
       Security Station which you can now access! Take the supplies and ???
       unlock the doors
    
       Continue re-tracing your steps. In the hallway, on the floor to the right,
       is a Hatch. Open it and drop down for SECRET 2.2. Find some The Possesseds
       and 2 Imps, along with ELITE GUARD 2.1 and a Plasma Rifle (SECRET 2.3). To
       get out of this area, you'll find a Grate that you can kick open.
    
       This will drop you into the location of the Developed Outdoor area fight,
       which is now vacant, but some Health may have re-appeared.
    
       Continue retracing your steps by pressing the Call Elevator button on the
       lower level, and find the Field Drone. I recommend using it to get the
       Heat Blast modification for the Plasma Gun.
    
       Now, instead of going forward, turn right into a door that was unlocked
       when you accessed the Security Station a minute ago. This is SECRET 2.5.
       Follow the blood to a duct, crouch, and go through to get to a steamy room
       you could see into earlier. SECRET 2.7, ELITE GUARD 2.2, and some armor
       and health.
    
       Exit the door by interacting with it, to the Industrial Train Depot.
    
       Go through the Yellow Keycard door, and Open the Airlock from the control
       room in this area. You'll find an Assault Rifle here.
    
       Enter the Airlock, then Cycle it to access the red outdoors.
    
    Mission 2: Fight: Outdoor Fight
    
       This sprawling fight occurs mostly in the lower level of a two-level area.
       It's mostly Possessed Soldiers and Imps- lot's of them. I recommend
       running through using Heat Blast, and using the Chainsaw on the Possessed
       Security. Then grab the Berserk Powerup to kill the majority of the
       remainder.
    
    Mission 2: Accessing the Secret after the Outdoor Fight
    
       Follow the uphill path from the entrance to the second floor. Right as you
       get onto the second floor, look for a bloody crate.
    
       Jump onto the crate, then jump up and forward onto a duct. Turn right and
       go shortly up along the top of the duct. Turn around and jump onto a
       higher, shinier duct.
    
       Walk along it, with breathtaking martian views, keeping an eye out for a
       yellow landing to the right of the duct.
    
       Jump onto the landing - and jump again to a rooftop.
    
       Walk through the building, turn left and go over a pipe, then turn right
       into a duct, to find SECRET 2.6, COLLECTIBLE 2.1: "Doom Marine Model,
       Doomguy".
    
       Go back - and on the rooftop look for a hatch that you can use to drop
       down into the control room with the in-game waypoint.
    
    Mission 2: Realigning the Communication Satellites
    
       There's a corpse whose handprint will grant you access to begin the
       realignment process. Interact to achieve this morbid security victory.
    
       Follow waypoints, to go down the elevator down to the next tiny fight.
    
    Mission 2: Fight: Tiny fight after realignment
    
       3 Imps climb up; one more on bridge.
    
    Mission 2: Crossing the bridge
    
       Jump across where the surprising Imp jumped up. Turn right and jump where
       a green light strip can be seen.
    
       There are symettric platform to the left (away from the base) and right
       (toward where you came from). Jump to the right.
    
       Take the platform back toward the building: there should be a suit of
       armor in front of you.
    
       An automatic door will open, with 2 Possessed Soldiers and 1 Possessed
       Security. Toss a grenade back in. The chainsaw can be a good way to deal
       with the Shielded guy.
    
       CHECKPOINT.
    
    Mission 2: Fight: Entranceway / Control Room Area
    
       Three Imps and a few The Possesseds.
    
       There's a assault rifle and CODEX ENTRY "Monsters / Possessed Security"
       here.
    
       In the control console area is a screen you can use to open the next door.
    
    Mission 2: Fight: Hallway
    
       A Possessed Soldier will run in as soon as the door opens.
    
       Many The Possesseds, 3 Possessed Soldiers, and one Possessed Security.
    
       Often the Possessed Security guards a hall to the left. It is worth
       exploring. After climbing, an Imp will spawn in front of you. There is
       ELITE GUARD 2.3 and a Munitions Crate.
    
    Mission 2: VEGA Console area
    
       This is a semicircular area with a central room.
    
       But first, climb the crates at left and jump to find SECRET 2.4,
       COLLECTIBLE 2.2, "Heavy Assault Rifle Model, Bronzeguy".
    
       Enter the central room and watch the cut scene.
    
       I recommend directing the Argent Energy toward your Health.
    
                             Mission 3: Foundry "Meltdown"
    
       This mission has 4 Gore Nests you need to destroy. The first two can be
       destroyed at any time. The third requires a Yellow Keycard and the fourth
       requires a Blue Keycard. Getting the Blue Keycard requires a Yellow
       Keycard.
    
       Here's a quick description of each Gore Nest:
    
         * Gore Nest 1: In the area behind the Field Drone
         * Gore Nest 2: In the main area on a damaged platform.
         * Gore Nest 3: Accessed by the Yellow Keycard, in a side-foundry.
         * Gore Nest 4: Accessed by the Blue Keycard, in a locker room area.
    
       The Main Foundry Area is the large open area with molten metal floors and
       platform-walkways.
    
       Notes on Combat Challenges:
    
         * Three Possessed, One Barrel: the easiest opportunity for this is early
           on, but you can also do it in the Argent Cell fight.
         * Curb Stomp: Gore Nest 2 in the yellow molten Main Foundry Area is the
           easiest, but there's a lot of random Possessed Soldiers around.
           (Unlike Mission 9's "Variety Is the Spice of Death II", Hell Razers do
           not count for this challenge)
         * Quite the Collector: easy with this guide, I hope.
    
    Mission 3: Gore Nest 1
    
       From the entrance area, exit into the Main Foundry Area. Jump left over a
       gap in the catwalk. To the right is a Possessed Soldier you can
       Death-From-Above Glory Kill (as needed for the combat challenge) and many
       possessed you can kill with one barrel (another Combat Challenge).
    
       Go back, though, through the door and find FIELD DRONE 3.1. Use it as you
       wish (I tend to like Assault Rifle's Tactical Scope). There is also CODEX
       ENTRY "Environments / Foundry" here.
    
       Keep going back past some firey doors to a control console. You can try to
       unlock the door (you don't have access) or watch a replay to see where the
       Yellow Keycard Guard has gone.
    
       If you turn so we are facing away from the control console, there are two
       passages: the entrance on the right, and the left passage has the keycard.
    
       If you enter that passage, you'll see that the catwalk has broken, and you
       should barely be able to see a deceased guard on the other side, leaning
       against a non-functional door: he has your Keycard.
    
       If you try to jump across, you'll land on a platform below. To your right
       is a small room with ELITE GUARD 3.1.
    
       Follow the green light to jump around and get up to a platform at the same
       height as you started. The highest platform should say MIXOM. Look around
       at you should see a square opening you can jump into: this is SECRET 3.1,
       there is a suit of armor here.
    
       Finally, jump to the platform you could see from across the gap. Interact
       with the corpse to grab his biometric ID (ie his arm). You can jump the
       gap easily in this direction. The flaming door ahead is where the Gore's
       Nest is located.
    
       Go to the control console and use the dude's arm. Turn left twice to find
       the Gore's Nest.
    
    Mission 3: Fight: Gore Nest 1
    
       This fight takes place in a somewhat dim and dirty one-story area. But,
       it's just ~5 Imps and ~3 Hell Razers so it is fairly quick.
    
    Mission 3: Gore Nest 2
    
       This gore nest is the only one in the Foundry's Main Area.
    
    Mission 3: Fight: Gore Nest 2
    
       Pre-Fight: A good place to use the heat blast, and a fine place to work on
       the Curb Stomp combat challenge. This is a mix of The Possessed, Possessed
       Soldiers, Imps.
    
       Gather supplies then destroy the Gore Nest.
    
       As suggested by the Gas tank near the Nest, you may wish to use chainsaw
       here since you might be low on ammo. Otherwise, just use a mix of weapons;
       I often mostly use Heat Blast here. This is a mix of Possessed Soldiers,
       Imps, and Hell Razers.
    
    Mission 3: Fight: The Tunnels Above Gore Nest 2
    
       This system of tunnels can be entered any time, except during combat. But
       you'll probably want to do it right after Gore Nest 2.
    
       It connects various stories of the Main Foundary Area overlooking Gore
       Nest 2.
    
       This is more of an exploratory area than a fight, but it is strewn with
       minor demons.
    
       It is hard to describe all the turns and the 3 entrances to this area, but
       it can be explored easily enough. Just make sure you find:
    
         * CODEX ENTRY "Monsters / Imp" in a dead-end room with some armor
         * SECRET 3.4: To get to this secret area, you'll have to jump up to a
           nondescript ledge. Look for a room with a rotating-red ceiling-mounted
           light, over which is painted "UAC-HAL". Looking at that, the duct is
           just to the right of it. Enter into it, and it'll twist around to get
           to the Secret, ELITE GUARD 3.3 and the ROCKET LAUNCHER.
    
       There are three access points, all overlooking Gore Nest #2. Here's a
       description of each of them:
    
         * Lower Entrance / Gore Nest #2 Access
              * From the vicinity of Gore Nest #2: looking out to the main area,
                the catwalks on the right should have two stories. Get to the
                upper story, and you'll find a small doorway.
              * From the tunnel, look for blood streams and an obvious exit.
         * Middle Entrance
              * From the tunnel: look for an observation room; the door it
                outside the window looking in.
         * Upper Entrance / Yellow Keycard Guy Access
              * From the guy: go out to a downward staircase; at its bottom turn
                into a small door.
              * From Tunnel: look for a green-lit room with 2 large white boxes.
                Stand on the box(es) and jump to a yellow patterned ledge.
    
    Mission 3: Fight: Obtaining the Yellow Keycard
    
       To get here, go out of the Field Drone area, and go straight veering
       around the Blue Keycard Area. Before you enter, you may see some Plasma
       Ammo.
    
       4 Imps, a Possessed Security and two Possessed Soldiers in back are ready
       to fight you. The Shielded guy is the biggest problem, and the chainsaw
       may be the most effective way to deal with him.
    
       Taking the Keycard creates a CHECKPOINT.
    
    Mission 3: Fight: Getting Away with the Yellow Keycard
    
       Exiting the area triggers the creation of 2 Imps, a Hell Knight, and (down
       the hall) 2 Possessed Securities. I usually run to the Field Drone
       location, lobbing a grenade behind me. The Hell Knight is the only big
       problem - in fact, often the other attackers will fight themselves to
       nothing if you merely wait.
    
    Mission 3: Fight: Argent Cell
    
       In order to use the Yellow Keycard, you'll have to find a mishmash of
       demons in a hot foundry area. The barrels provide an easy way to kill them
       en masse.
    
       ARGENT CELL 3.1 is found in the corner, in front of a defunct door.
    
       SECRET 3.3 is the classic doom level. From the yellow keycard area, look
       back on the walkway you came in on. There should be a box/crate on its
       right side. On the side of that is a Lever, which will open a door in the
       fight area that enters CLASSIC MAP 3.1 "Doom - Nuclear Plant".
    
    Mission 3: Using the Yellow Keycard
    
       As you approach the yellow keycard door, a Hell Knight will surprise you.
       Entering the door creates a CHECKPOINT, so it is advisable to stock up on
       ammo, armor and health before entering.
    
    Mission 3: Fight: Hall after Yellow Keycard, before Gore Nest 3
    
       After picking up whatever supplies from the anteroom, including CODEX
       ENTRY, "UAC Personnel / Samuel Hayden", enter a hall where some repair
       robots appear to be working on a crate.
    
       Initially there are just two Possessed Soldiers (on the left-hand side) If
       you stay near the entrance wall, nobody else will spawn, and it is
       suggested to kill these guys before charging in.
    
       Then, a Hell Knight, a (few?) Imps, an a few Hell Razers will spawn.
       Lobbing a grenade at the barrel can help, but the Hell Knight has to be
       dealt with.
    
       SECRET 3.5, COLLECTIBLE 3.1, "Plasma Rifle Model, Prototypeguy" can be
       found in a crate being robotically worked on (climb on top of it then
       inside).
    
       SECRET 3.2, ELITE GUARD 3.2, can be found by climbing crates at the back
       of the room. There should be a chainsaw resting against the crates
       (initially).
    
    Mission 3: Fight: Gore Nest 3
    
       A Possessed Soldier and Possessed Engineer constitute the pre-fight for
       this Gore Nest.
    
       Destroy the Gore Nest.
    
       A few Imps and a few Hell Razers will spawn, and the finale is a Hell
       Knight.
    
    Mission 3: Finding the Blue Keycard
    
       The map should probably show the Auto-Map - it's on the catwalk area.
    
       Exit through the upper down in this area and you'll immediately run into
       the Blue Keycard holder (a corpse). Take the keycard.
    
       Drop down to the area where you "found" the Yellow Keycard. This is a good
       time to get SECRET 3.6, COLLECTIBLE 3.2, "Possessed Engineer Model,
       Vaultguy". Look for the 3 streams of molten metal. Get onto the walkway in
       front of them, and look straight down to see a little landing just inches
       above the molten metal. Jump onto this platform and look for the doll.
    
    Mission 3: Fight: Gore Nest 4
    
       There's no pre-fight: destroy the Gore Nest.
    
       This two level area has a sheltered locker room on the lower floor, where
       one Imp will spawn immediately but most of the demons (Imps and Possessed
       Soldiers) spawn upstairs. Lob grenades or charge in - eventually they'll
       come down the stairs, but slowly.
    
       It ends with a Hell Knight - since there's Gas, a chainsaw is a good
       approach.
    
       The upper story has a Health Station.
    
    Mission 3: Once all four Gore Nests are destroyed
    
       You may be ambushed by some Imps as you find your way to the waypoint.
    
       The Turbine Room door, which the game will guide you to, is now unlocked.
    
       POINT OF NO RETURN: Once you enter this area, you can't return to get
       anything. Also, you will get a CHECKPOINT before a big fight, so it is
       advisable to stock up on supplies before entering.
    
    Mission 3: Fight: Turbine Room
    
       This fight as two waves, both consisting of Imps and Hell Razers (XXX: are
       there PS?). At the end of the first wave is 1 Hell Knight; the second wave
       ends with 2 Hell Knights.
    
       After completing the fight, exit at the top of the room, on the opposite
       side as the entrance.
    
    Mission 3: End of Mission
    
       You come into a hall with ELITE GUARD 3.3 propped up on the left side.
    
       Open the Shutters (interact with the screen), to watch a cut-scene with
       Olivia Pierce.
    
       Immediately after that, an Imp and 2 The Possesseds will spawn.
    
                   Mission 4: Argent Facility "Beginning of the End"
    
       Notes on Combat Challenges:
    
         * Walk the Path and Bird's Eye View: easy with this walkthrough,
           hopefully.
         * To Be Knighted: this is pretty hard since these guys are so tall. The
           Dazed and Confused rune can be useful to give you more time to figure
           out how to jump over them - it usually requires jumping from above,
           unless they are crouched. Of course, a cheesy way is to replay this
           mission after you have the Jump Boots which make it substatially
           easier.
    
    Mission 4: Introduction
    
       Go forward and Open the Airlock to find yourself in an industrial open-air
       area: immediately in front of you is a trash fire and ahead of you is a
       blocked-off bridge.
    
       Look left. There should be a octagonal structure with 2 Platforms, a Lower
       one and an Upper one. Jump to the Lower Platform. Now, look left for some
       green marker lights on the cliff-like rocks. Jump up a few of them (follow
       the green marker lights), and on to the Upper Platform.
    
       Now, look for an broken bridge - jump there and cross another small
       bridge, to your first Rune Challenge: "Vacuum". This challenge is not too
       bad, and the rewards are quite good, so you should do it. Time is really
       of the essence on this challenge.
    
       After succeeding at the Rune Challenge, the Rune is NOT automatically
       equipped, so go to the Rune section of your Dossier and select the Vacuum
       Rune.
    
       If you want, grab the ammo on the right pathway, but the mission continues
       to the left.
    
       In front of a closed door, you'll see some Health and Ammo, and CODEX
       ENTRY "Environments / Argent Facility". Less obviously, befind some
       barrels to the left, is a Classic Doom Level Lever - the lever is in the
       dark and hard to see. Pull it: the "retro" level itself will be easy to
       see ahead.
    
    Mission 4: Fight: Gore Hallway
    
       Enter the automated door to a hallway that has been thoroughly decorated
       with entrails. Midway down this hall, to your right, is (assuming you
       pulled the lever above) the SECRET 4.5, CLASSIC MAP 4.1 "Doom - Toxin
       Refinery".
    
       Continue out the hall to run into 2 Possessed Securities and a bunch of
       The Possesseds. Some Imps will spawn soon; once you kill them you'll get
       more Imps and a Hell Knight.
    
       You can retreat into Hall (and it can be a good way to start the fight,
       say, with a few Grenades). But the new monsters will start to spawn behind
       you, and it may be easier just to stay in the open.
    
       CHECKPOINT.
    
    Mission 4: Fight: Force-Field Gore Nest #1
    
       Jump over a crude but wide blockade to get to a view of a big glowing
       rectangular blue force-field. The gore nest is just behind it.
    
       Looking down, you may see some Imps fighting - they will see you soon
       enough. Kill these few Imps, along with the Possessed Engineers and The
       Possesseds stumbling around.
    
       Destroy the Gore Nest.
    
       You'll have to deal with 2 Hell Knights, 2 Hell Razers, and a bunch of
       Imps.
    
       CHECKPOINT.
    
       It's probably worth going back to the Blockade you entered from, and look
       around for a cave (it'll be on the left as you walk toward the Force
       Field). The cave has ELITE GUARD 4.1. There's some ammo (etc) here.
    
    Mission 4: Fight: Argent Cell
    
       (It might seem logical to destroy the Argent Filter associated with the
       Gore Nest first, but due to how the Checkpoints work, I suggest doing
       things in this order)
    
       You can now go and destroy the Argent Filter, but I think it makes sense
       to first deal with the Argent Cell.
    
       The Argent Cell is in the building on the left side of the force-field
       when looking at it - on the opposite side of the gore nest from where you
       entered. There should be some Health in front of it.
    
       Entering, there will above 5 Imps spawned gradually.
    
       Once they are gone, CHECKPOINT.
    
       Now, find ARGENT CELL 4.1 behind some tanks. Use it: most players will opt
       for Health.
    
    Mission 4: Argent Filter associated with Gore Nest #1
    
       Open the small door on the lower floor near the Gore Nest's old location.
       Enter to find a Possessed Engineer and a few The Possesseds. There is also
       CODEX ENTRY "Personnel / VEGA". Make a left to follow the waypoint and
       interact with the Argent Filter for a cut scene.
    
    Mission 4: Under the Force Field (Optional)
    
       There's a small treasure area directly below the big blue force field.
       Face it, and go left down a path (which has a Munitions Crate). Turn right
       and descend 3 floating Islands of rock to get to a partially open bay door
       (visible from above).
    
       Inside you'll find Gas, shotgun and plasma ammo, and a little armor. But
       most importantly FIELD DRONE 4.1.
    
    Mission 4: Fight: Tank Gore Nest #2
    
       Near the entrance for the Argent Cell building, find two stacked crates,
       and a suspended one: these can be climbed, and from the top of the
       suspended crate, you can jump to the second floor of this building.
    
       This battlefield is distinguished by a recognizable and large Union
       Aerospace tank (which you can jump on).
    
       Pre-Fight: 3 Imps run down from above very quickly, be prepared to take
       care of them.
    
       Fight: Imps and Hell Razers with 2 Hell Knights.
    
    Mission 4: Argent Filter associated with Gore Nest #2
    
       Go into the closest door to Gore Nest 2, on its same level - it is
       somewhat inset - a waypoint should be leading in this general direction.
       Inside the building, go along the walkway to a closed green door with the
       waypoint behind it by 15 meters. Enter and interact to destroy the Argent
       Filter #2 and get a CHECKPOINT.
    
       There is also a Plasma Rifle here.
    
    Mission 4: Rune and Secret
    
       From the small room containing the Argent Filter, turn right to a large
       floor with large lifts. You can probably see the glowing green RUNE
       CHALLENGE 4.2: "Dazed and Confused" on the lift in the opposite corner of
       the building (from the entrance, look at the opposite corner - the rune is
       on the structure just to the right of center).
    
       Once done with the rune, look for a large hole that is serviced by a lift
       (now down). Jump down there, and into a hallway. On the left you should
       see a small block on a larger block, making a natural stairway. (A drone
       delivers it- wait a few seconds if the blocks aren't climbable.) Climb up,
       and turn right to see a service walkway which you can jump onto to find
       SECRET 4.2, COLLECTIBLE 4.1, "Hell Knight Model, UACguy".
    
    Mission 4: Back Access Walkway (Secrets, Optional)
    
       This lonely walkway is the only dirt path descending from Gore Nest #2 /
       Union Aerospace Tank. It provides alternate accesses to a Lab and the Icy
       Gore Nest #3; these are described below. It has a broken bridge midway.
    
       If you face the Union Aerospace text on the large tank, go down the dirt
       walkway to its left. It is the only dirt walkway descending from this area
       - it'll turn to a metal grated walkway - then there's a gap you must jump.
    
       Look to your right for a misty cargo alcove with a lone crate. Jump on it
       to get to the second level.
    
       You should find a Munitions Crate here.
    
       A single Imp will pop out if you follow the walkway to its end.
    
       If you stand on the platform at the edge of building, you should see a
       rectangular duct that runs along the outside of the structure. Walk on it
       for a bit until you get to the next alcove: enter to find SECRET 4.3,
       COLLECTIBLE 4.2, "Rocket Launcher Model, Stealthguy".
    
       Go back to the first alcove, but jump across to a green-lit cliff; jump
       again to a walkway and kill a few demons (a Possessed Engineer and a few
       Possesseds). (This is helpful to get the maximum combat rating)
    
       Finally, go to the end of the walkway (it becomes a catwalk) to a door
       (entrance to the Icy Area). Watch out for the Imp! At the end, go left
       onto a natural walkway. This is SECRET 4.4. There's a Possessed Engineer
       and a few Possesseds, but most importantly, the SUPER SHOTGUN.
    
    Mission 4: Lower Area with Elite Guard #3
    
       Start at the Force Field (Gore Nest #1) - when facing the field, go down
       the path to the left.
    
       You should see an active door, and a series of plateaus that lead to a
       Munitions Crate. Immediately to the right of that is a level path that
       becomes a sidewalk for a building. Some Possesseds appear here. At the end
       of the walkway is ELITE GUARD 4.3.
    
    Mission 4: Fight: Lab (Optional)
    
       This area has a Health Station, FIELD DRONE 4.2, Gas, and CODEX ENTRY
       "Monsters / Hell Razer", but isn't necessary to the completion of the
       Mission.
    
       Field Drone #2 is on the upper level - it can sometimes take a few seconds
       to fly in once combat is over.
    
       It has two entrances:
    
         * Normal: From the site of Gore Nest #2 / the Union Aerospace Tank,
           climb a crate to a balcony. The door enters the middle story of the
           Lab.
         * Sneaky: From the site of Gore Nest #2, walk down a dirt path to an
           enclosure with some blocks on your right. If you look up, you should
           see a greenlit ledge to your left, which is your goal. Climb onto the
           blocks, at right, then onto a grating looking onto the greenlit cliff.
           Jump across and open the door to be in the lower story of the Lab.
    
       The Possessed Guards tend to be in the lower story and entering there
       catches them more unawares, maybe.
    
       There are also 5? Imps and a bunch of Possesseds and Possessed Engineers.
    
       You'll get a CHECKPOINT when the bad guys are cleared.
    
    Mission 4: Fight: Icy Gore Nest #3
    
       There are 3 entrances to this area:
    
         * Lower Entrance: from Gore Nest 2 (the Union Aerospace tank), go down a
           dirt path to where it becomes a catwalk instead, to the end at a
           active motion-sensing door.
         * Mid-Lower Entrance: This is probably the "main entrance". From the
           blue force field, go on the path on its left side to a building
           labelled in large letters "COOLING TOWER".
         * Upper Entrance: Access from the long curved exterior walkway with
           Elite Guard #2.
    
       It matters little.
    
       Prefight: you'll have to deal with 5? Imps and 2? Possessed Soldiers and a
       bunch of The Possesseds.
    
       SECRET 4.1: You can actually use this area at any time.
       It is the through the door on the lowest floor area. There's the Auto-Map
       in here, and it'll CHECKPOINT. Of course, the Auto-Map achieves the
       "Bird's Eye View" Combat Challenge.
    
       Fight: Once the Gore's Nest is destroyed, 1 Hell Knight spawns immediately
       along with a wave of Hell Razers and Imps. There's Gas on the second level
       (and other supplies) in case you want to chainsaw anyone.
    
       Post-Fight: Now, go in to destroy the Argent Filter.
    
       There's a Munitions Crate, Gas??, a Health Station, CODEX ENTRY "Monsters
       / Hell Knight". Destroy the Argent Filter and go outside for the last
       battle in this icy area.
    
    Mission 4: Fight: Destroying the Icy Argent Filter
    
       This is your introduction to the Summoner. She will spawn centrally the
       instant you exit the control booth. The Rocket Launcher (especially with
       Lock-On) is a nice approach, as is the Chainsaw, but she can really be
       killed by any weapon.
    
       Besides her, there are 3? Imps and a Hell Razer, making this an otherwise
       small fight.
    
       CHECKPOINT.
    
       I recommend leaving the building through the top exit, above the Auto-Map.
    
       You'll be on a walkaround that going alongside the building, a few
       Possesseds and a Hell Razer will surprise you be spawning in front of you.
    
       At the end of this walkway, find ELITE GUARD 4.2.
    
    Mission 4: After Destroying the 3 Argent Filters
    
       A new Gore Nest will appear: it's on the upper story and easily visible.
       You have to get to it from the building below, which once housed ARgent
       Filter #2.
    
       Climb the crates, following the waypoint to the upper-story of the huge
       hangar, right next to Rune #2.
    
       Exit the door toward the waypoint (approx 80m away), stocking up first if
       necessary and possible. There should be a Munitions Crate ahead, and to
       the left is the exit to the Gore Nest.
    
    Mission 4: Fight: Final Gore Nest
    
       Pre-Fight: there are 2 Possessed Soldiers, a Hell Razer, and an Imp.
    
       Destroy the Nest.
    
       Fight: a Hell Knight and a Summoner are the main act in this fight -
       there's also a few Imps and Hell Razers. However, there's a Berserk
       Powerup, which compensates a lot (in fact, if you have all the Powerups
       for the Praetor Suit, you can probably kill everything with that single
       Berserk Powerup).
    
    Mission 4: Destroy Primary Argent Filter
    
       Enter the building and face left for ELITE GUARD 4.4.
    
       Follow the waypoint to another Argent Filter (looks like the others).
       Destroy it, and watch the cut-scene.
    
       Follow the waypoint and Exit the Facility.
    
                     Mission 5: Argent Energy Tower "Argent Tower"
    
       We start the level getting new Jumping abilities, the Jump Boots. Then we
       cross a damaged bridge to the Tower itself.
    
       The tower is big and tall - most of the level is spent ascending it.
    
       Notes on Combat Challenges:
    
         * Chiropractor: Imps are a bit scarce in convenient locations. There are
           a lot on the bridge, but you'll have to be slightly patient to lure
           them into Glory Kill range, and even then sometimes they'll be at the
           back of a platform and it's not possible to get behind them. There are
           a number in the fight outside the tower, including 4 near the entrance
           to the fight (and checkpoint). There are a few in the first big fight,
           and there's 4 scattered at the upper regions of the tower. Finally,
           there's some in the giant fight at the end of the level.
         * Searching High and Low: easy.
         * Overkiller: there are 3 Quad Damage Powerups: in the fight just
           outside the tower, in the fight in the base of the tower, and in the
           truncated big fight at the end of the mission. It is quite possible to
           achieve this in any of those fights: as long as you use the powerup
           you'll probably be fine. I recommend Plasma Gun/Heat Blast for bulk
           killing.
    
    Mission 5: Fight: Intro to Level, and Revenants
    
       You start on a useless platform, and have to jump left to get to the
       Maintenance Hangar that VEGA alludes to. Upon entering the building, look
       right, and you can see a Revenant eating a corpse. It soon comes down to
       attack you. There are a gaggle of demons on the floor below you, and more
       will spawn. In total, there's about 3 Possessed Soldiers, 3 Hell Razers, 3
       Possessed Engineers. (No Imps, unfortunately, as it would help with the
       Chiropracter challenge.)
    
    Mission 5: Maintenance Hanger miscellany
    
       Enter the locker room and retrieve the Jump Boots, as well as CODEX ENTRY
       "Environments / Argent Energy Tower", various Ammo, and a Health Station.
    
       Exiting the locker room, go right (back toward the entrance) and
       double-jump up onto a platform; U-turn and look left for another platform
       to up-jump. Then down-jump into an enclosed area with a Rune Challenge
       (which was visible from before through some steamy glass), a suit of
       armor, and Gas can. To exit this area, jump down.
    
       Jump up the same platforms used to access the RUNE CHALLENGE 5.1 "Ammo
       Boost", but look across the area for a floor you can jump to, under a
       low-beam; some armor is at the end of the jump. To the right is a crate
       and some rockets, but ignore them for now, and go left. There is a
       platform to jump up on, and if you look around, you'll see another
       green-lit platform above to jump on. Looking around from the top platform,
       you should see a pink-lit short alcove that you can drop into: there's
       SECRET 5.1, ARGENT CELL 5.1 here.
    
       Hints on Rune Challenge, "Ammo Boost". The challenge is to not miss anyone
       - I find that I jump make 1 1/4 laps around the periphery of the area,
       looking into the center to shoot any stragglers.
    
       Ammo Boost isn't exactly necessary, but it (and its upgrade) make ammo
       much more available - especially BFG ammo, once you have the Upgrade and
       of course the BFG itself.
    
    Mission 5: Crossing the Bridge, and Secret Guardhouse
    
       Before crossing: make sure you have Argent Cell #1 and Rune Challenge #1.
    
       The bridge starts with a crate and some Rockets. Use the crates to jump
       left onto the bridge proper. Continue along. You'll jump down to a
       platform.
    
       At this point, you can expect to be ambushed by ~8 Imps, 2 at a time. They
       are all over this gigantic damaged catwalk bridge, you can kill them,
       ideally by Glory Killing them from behind, to work on achieving the
       Chiropracter Challenge.
    
       As you are working over, you'll go through a pair of tunnels. The flat
       area ahead is where I usually kill the Imps, letting them come to me. It's
       big enough that I can often get a few Neck Glory Kills.
    
       From the tunnels, you can and should access FIELD DRONE 5.1 and a SECRET
       5.2. Get on top of either tunnel, and double-jump across to a platform (it
       has a green light). Jump left up a series of airy platforms to an enclosed
       bluish area with 8 The Possessed stumbling about with a Possessed Engineer
       on the upper deck (near a suit of armor). Right outside (on a bridge) is a
       Possessed Security.
    
       Across the bridge is a guard house, which is Secret #2. Inside is a Hell
       Knight who will charge at you; and 2 Possessed Soldiers and a Possessed
       Security who will stay in the shed. Take them out to find Field Drone #1,
       some health, CODEX ENTRY "Monsters / Revenant". Continue along a walkway
       to some armor.
    
       When done, jump down to a long walkway that goes almost the whole length
       of the bridge. There's a long gap that have been torn apart: you'll have
       to double-jump.
    
    Mission 5: The Far Side of the Bridge
    
       After the destroyed section of the bridge, look down and right to see
       ELITE GUARD 5.1 (SECRET 5.3) propped up against a wall. Jump down. Getting
       back up is slightly more difficult: jump across the gap to jump nearly
       vertically up a few ledges, looking for green lights (a yellow ledge for
       the last jump).
    
       Note: You can get back, but it's not necessary and more difficult than
       jumping forward.
    
       Cut scene.
    
       Enter the next room to find a Health Station, CODEX ENTRY "Monsters /
       Summoner", and most important Auto-Map.
    
    Mission 5: Fight: Tower Exterior
    
       Enter the next area to surprise 2 Imps. Looking at the Imps, there's some
       Plasma ammo to your left. Ahead, the platform has an upper outer story and
       a lower inner story. Further ahead, on a higher platform, is a Quad
       Powerup - it glows purple brightly.
    
       It's fairly easy to get a Neck Glory Kill on an Imp, then grab the Quad
       Powerup and use Plasma Gun / Heat Blast to kill basically everything.
    
       The monsters who are here or will spawn are many Imps and Hell Razers, and
       2 Summoners.
    
       Leave this area through a Maintenance door on the far end.
    
    Mission 5: Lower Railway (Description and Secret)
    
       As you can probably see by the Map (in the Dossier), you are at the
       outside of the tall circular Argent Energy Tower. Unmanned trains run
       around it's exterior, and you'll encounter them a few times.
    
       You should see such an unmanned train going right every 5 seconds or so.
       Use the Munitions Crate, then follow the next convenient train, and drop
       into an unused track. Keep going, and you should see an entrance to a
       human-sized passageway on your left.
    
       Upon entering the passageway, look back to find ELITE GUARD 5.2. Continue
       to find a Health Station and Codex Page "Database / Argent Energy".
    
       At some point, the passage becomes narrower and darker, and we can make a
       detour to get the Collectible doll.
    
       To get SECRET 5.4, COLLECTIBLE 5.1: "UAC Pistol Model / Orangeguy",
       re-enter the unused Train corridor at this point (by veering right).
       Continuing down the corridor, you'll arrive at an unused, stationary train
       car. Get onto it, by double-jumping onto the ledge to your right, then
       double-jumping onto the train car (don't worry: the upper-train won't hit
       you). You should be able to see another dimly-lit ledge near where the
       upper train cars keep entering. I found this jump to be quite tricky. but
       the trick is that you must be facing at the ledge (ie facing perpendicular
       to it / straight at it), which mean you must jump almost sideways, which
       in turn makes dodging the train above more difficult. Once you are on this
       ledge, turn left and go up (parallel to train), then turn around and jump
       into the hole that the train is entering. You must keep moving, but when
       you run out of floor, drop to the left, and you'll find the Model. Drop
       down the train area to get back to the Elite Guard, and continue back to
       where the passage narrows and becomes darker.
    
       OK, continue down this short dingy corridor, and you'll find a Hatch, at
       left, along with some a rocket launcher.
    
       POINT OF NO RETURN: Dropping down this hatch is irreversible, and a
       CHECKPOINT is created immediately on hitting the ground.
    
    Mission 5: Fight: Base of Tower
    
       This fight begins with a cut-scene introducing us (somewhat) to the
       Mancubus.
    
       Use the Rocket Launcher or Gauss Cannon (etc) to damage this guy before
       running around for a while taking pot-shots at various demons.
    
       Once you damage a lot of demons, look for the Yellow Lift that jams you
       into a Qad Powerup. Use Plasma Rifle's Heat Blast to kill a lot of demons.
    
       Post-Fight: pick up all the Gas and Ammo.
    
       Midway up there's a tricky little secret. You'll find to and area where
       the central red beam (of Argent Energy) since surrounded by rotating and
       stridulating metal shields.
    
       Continue up, across a long jump to where the red beam is protected by
       shutters that periodically open and close. Look on the map. You should see
       two symmetric arms going up. But one of them has a walkway underneath.
       This is SECRET 5.5, COLLECTIBLE 5.2 with "Summoner Model, Purpleguy". With
       the In-Flight Mobility Rune, this is a piece of cake, but you don't have
       that yet, so you'll have to use one of two approaches.
    
         * You can actually jump on the gray tubes that run to the platform, then
           jump again onto the platform.
         * Drop from a platform above, and jump in mid-air onto the duct.
    
       Resume climbing: there's a rotating train that repetitively inserts ducts
       into the central beam. Between when it opens and when it extends the duct,
       you can jump up.
    
    Mission 5: Fight: Midway
    
       A fight involving Possessed Soldiers, Imps, Revenants and a Hell Knight
       breaks out here. There's a somewhat tricky-to-get-to Invulnerability
       Powerup that can help. It can found be looking for the two protected doors
       a few stories up from the ground level. One is your waypoint (it has a
       suit of armor in front) and the over has the green Invulnerability
       Powerup. Use the blue lifts to get onto this high area.
    
       After the lockdown is disengaged, continue up to where the waypoint is.
    
    Mission 5: Activating the Drones
    
       Use ARGENT CELL 5.2 and the Health Station if needed, and interact with
       the screen (at waypoint): "Activate Drones".
    
       This will cause two pairs of cars (drones) to transport stuff vertically
       from this area to a platform above: we'll catch a lift.
    
       Exit the control room and find that there's one pair of drones right in
       front of you.
    
       Instead, go around to the opposite side of the column where the second
       pair of drones is (this is also where the Invulnerability Powerup is).
       Jump onto a drone and go up: you'll see a platform at the top, with (if
       you look carefully) a lever. Jump to it and actuate the Lever. Hitch a
       ride down with the drone. At the bottom, the drone will plug into a
       socket; when it disengages, you'll see SECRET 5.7, the CLASSIC MAP 5.1
       "Doom - Halls of the Damned" in the back of the socket.
    
       After that, take any drone up to the top and jump up to the highest
       platform you can. You'll see another rotating plug train. When it stops
       you should be able to jump straight onto it. When it stops again, follow
       the plug and some on to a platform on either side.
    
       From this narrow inner circular walkway, you'll see 4 arms ascending to
       the outer side of the tower. One of them has a couple of platforms by its
       end: you'll have to take that one, and jump up a few platforms.
    
       Keep going up, steering clear of the argent beams and taking out 4 Imps.
       Eventually you can hitch a ride up on one of the argent transfer things.
       From the top, the waypoint is right there: a greenlit door to force open.
    
    Mission 5: Fight: Upper Office
    
       2 Possessed Solders and a bunch of The Possessed await you inside.
    
       From the office, take the stairs to a Possessed Security, a Hell Knight,
       and a few more minor demons. The passage comes to a dead end.
    
    Mission 5: Ascending to the Top
    
       From the dead end, you can jump across the tracks through a "window". To
       your left will be Rune Challenge #2, "Equipment Power".
    
       "Equipment Power" is a pretty easy and fun challenge. Simply use yourself
       as bait to lure the Unwilling into barrels that you shoot. Watch out for
       Unwilling that spawn behind you though!
    
       After the Rune Challenge, look back across where you jumped the tracks,
       and notice a higher platform you can jump to.
    
       You come to a pair of elevator shafts. The first one (on the left) has a
       Munitions Crate in plain view. The second one has a Mega-Health down in
       the shaft. Drop down to get it, and retrace your steps.
    
       From the Munitions Crate, jump onto an obvious ledge system to another
       hallway.
    
       Before going on, look at the twin elevator shafts. Between them, in the
       hall is a wide brown pillar with orange lettering on it ("UAC E-1" on one
       side, "U-A 46.2" on the other). There's a landing in back between the two
       elevators: ELITE GUARD 5.3 is here.
    
       Continue up the stairs and through the door to another elevator shaft on
       left, and audio of Olivia.
    
       Carefully peer down the elevator shaft - you'll see an opening about 6
       lights down: jump and hold forward to land in it - this is SECRET 5.6.
       Here we acquire the Gauss Cannon, the most powerful "standard" weapon.
       "Open the Turbine" by interacting with the screen, which will open a exit
       from the shaft.
    
       Take it, and retrace your steps all the way back up to the top of the
       shaft. Note there's a Hologram (sometimes known as a Decoy) and a Plasma
       Gun here.
    
       Now, jump up to the landing at the far side of the shaft and look at the
       shaft ceiling to see 4 red glowing things - each with a waypoint on it.
    
       Shoot them to cause a car to fall exposing another higher landing you can
       jump to.
    
    Mission 5: Pseudo-Fight: Before the Countdown Ends
    
       You could conceivably use this to do some Weapon Upgrade Challenges or
       Rune Challenges, but I usually focus on trying to conserve my 200/200
       which means perservering for a long time, then taking the Invulnerability
       Powerup at some point.
    
       Another use is to earn Combat Challenge progress. If you killed everything
       else, you should already have the highest Combat rating, but you can get
       just about a full circle if you fight very aggressively here.
    
       TODO: Timings
    
                      Mission 6: Kadingir Sanctum "Into the Fire"
    
       Notes on Combat Challenges:
    
         * Dead Man Stalking: these guys can be easy to miss.
         * Momentum Swing: fairly easy if you use all the powerups (just don't
           "save" them for too long).
         * Sweep the Leg: there's not a huge number of these guys in convenient
           locations, and the glory kill is a bit hard to execute anyways. Don't
           miss any opportunities!
    
    Mission 6: Fight: To get the Yellow Skull
    
       Because there are no Checkpoints, this sequence of fights is gathered
       together.
    
       First, drop down to a plateau with a toxic pond and 3 The Possesseds -
       target-practice. There's some armor. Jumping across to Plasma Ammo, maybe
       a Gauss Cannon.
    
       Climb up the stairs and kill 3 The Possesseds.
    
       This is one opportunity to get SECRET 6.4: after killing The Possesseds,
       look up and to your left for a rock ledge you can jump onto, then a
       sequence of 2 more ledges to get a suit of Armor.
    
       Venturing out will begin the pre-fight; the main fight won't begin until
       you get near the left edge.
    
       Look down to the next lower platform and you'll see an Imp spawn: you can
       kill it immediately with a grenade. Then a Revenant spawns: I usually use
       the rocket launcher, but whatever works.
    
       Stand on ledge that has a suit of armor on it. Look down below into the
       Main Pit Area, and soon you'll see 2 Mancubi lumbering around that you can
       carefully attack with the Rocket Launcher (preferably with Lock-On
       modification).
    
       Quickly jump down the Pit area, to trigger two waves:
    
         * a bunch of Imps and a Hell Razer, ending with a Hell Knight
         * a bunch of Imps and a few Hell Razers, ending with 2 Hell Knights
    
    Mission 6: Accessing and Using the Yellow Skull
    
       The game's waypoint will lead you to a switch (only accessible once all
       the above demons are killed). After actuating the switch, walk across the
       pit to a newly opened area with armor and the Yellow Skull.
    
       Now, find the Yellow Skull Door, by walking up the path from where the
       last fight started. Open the Door to walk in and find CODEX ENTRY
       "Artifacts / Slayer's Testament #1" and ELITE GUARD 6.1.
    
       Proceed onward to the next fight.
    
    Mission 6: Fight: 2 Summomer Fight
    
       This fight starts on a plateau overlooking another pit area with T-shaped
       bridges running atop it.
    
       If you enter but don't move, there are 3 The Possessed you can kill. Once
       you walk out toward the middle of the level, 3 Imps spawn.
    
       Once you get to the edge of the plateau is when the bulk of the demons
       spawn. On the center of the bridge, a Summoner will spawn. Lock-On Rocket
       Launcher is a good way to get her (as suggested by the Weapon Upgrade
       challenge). Another Summoner spawns on the left side of the lower area.
    
       2 Hell Knights soon spawn, along with a mess of Hell Razers (etc).
    
    Mission 6: Getting the Blue Skull
    
       Follow the game's marker to a Chainsaw and Shotgun Ammo. Continue down a
       passage to watch a series of islands appear, in the large cavern where the
       first fight began.
    
       You can jump directly to the nearest island, or jump down and make
       slightly easier jumps up the islands. (If you want armor, this is your
       second chance to get SECRET 6.4: you can see the suit of armor from above:
       climb the stairs and use some ledges to jump to it) In either event, a
       Skull-Switch is at the top of the islands; pressing it, you'll see a gate
       lift on the lower level. Jump down there, killing The Possesseds flailing
       around.
    
       The green mist will teleport you to the next area; before doing that, head
       right to pick up supplies and SECRET 6.1, COLLECTIBLE 6.1: "Revenant
       Model, Astroguy".
    
       Head through the teleporter.
    
       You'll find a Blue Skull. Upon taking it, a gate will open leading you
       back to the overlook of the Main Pit Area.
    
    Mission 6: Fight: Main Pit Area, part 2
    
       Before you can do anything, 4 Imps will spawn up here.
    
       Imps should start spawning below: carefully take them out with grenades or
       whatever.
    
       A few Cacodaemons will spawn. Two blasts with the Lock-On Rocket Launcher
       will kill them, or you can target their eye with the Assault Rifle, or
       Gauss Cannon works. You'll also need to keep lobbing grenades to kill the
       Imps that like to hang out in the area to the right of the base of the
       long stairs.
    
       At some point, to trigger more demons, you'll have to descend to the
       floor. Take the Quad Powerup as needed (if you have 2 Power Upgrades,
       you'll refresh your health at this point, so it can be best to wait until
       you are damaged. There is a wave of Revenants and a Hell Knight, another
       Cacodaemon, more Revenants, a Mancubus, and a number of Imps.
    
    Mission 6: Rune Challenge and Using the Blue Skull
    
       POINT OF NO RETURN: This Rune Challenge is only accessible for a short
       while. The protective gates around it are closed before you get the Blue
       Skull, and after you pass through a holographic ritual taking place in a
       corridor. (XXX: is the Rune accessible during the above Fight??)
    
       Accessing RUNE CHALLENGE 6.1 requires jumping onto the central Rock that
       held the Quad Powerup. Jump onto the smaller upper island (there are two:
       jump toward the one closer to the Blue Door?). Then you should see a
       man-made (or demon-made) ledge to your right, with a few small Healths.
       Jump, and turn around and look up to see a higher island. Jump to it -
       then continue the same direction to an upper ledge. Climb a short ledge to
       a tunnel leading left to the Savagery Rune Challenge.
    
       After finishing it, go back to the main rock (where the Quad Powerup was),
       and jump to the "balcony" with the Blue Skull Door. Interact, and you'll
       be in a pale green stone hallway: immediately on your right is an alcove
       containing Gas and a ARGENT CELL 6.1. Further down, is rockets.
    
    Mission 6: Fight: Misc Small Fights in the Cliff Area
    
       First up, is 4 Unwilling (good Weapon Upgrade fodder for Super Shotgun or
       Heat Blast) with a Mancubus, and a second Mancubus that jumps up with the
       first dies.
    
       Now is not a bad time to use the Invulnerability which is on a lower level
       near where you exit the tunnel.
    
       Walking along the ledge, some Imps, 2 Lost Souls, a Revenant spawn.
       (Another good strategy here is to retreat and pick them off with the
       Assault Rifle. Often they'll kill each other)
    
       Island-Jump across to be surprised by 3 Lost Souls, and a Hell Razer. The
       HR can be used to work on the Combat Challenge.
    
       Walk through the tunnel behind the Hell Razer, and you'll be on a new
       cliff, with a fire and ELITE GUARD 6.2. First, look left and down and
       you'll see the first Cacodaemon. There is second one, probably behind that
       rocky pinnacle. Lock-On Rocket Launcher is a fool-proof way to deal with
       these guys.
    
       Visit the Elite Guard.
    
       Detour for SECRET 6.2: Jump to the Island with the Armor and jump across
       to a lower ledge. Turn right, and a Hell Knight will spawn. Behind him (to
       the left) is a small cave with the Chaingun (the cave is the secret).
       Retrace your steps to the spent Elite Guard across the cavern.
    
       Island-Hop using the upper chain of islands. At the end of this sequence
       of 5? Islands is a Skull Switch: you will see the Iron Gate to the next
       part of the level raise when you actuate it.
    
       You won't get a CHECKPOINT until everything is cleared (except the Hell
       Knight)- usually that occurs after the pair of Cacodaemons.
    
    Mission 6: Fight: Second Pit
    
       Enter to find yourself in yet another large arena centered around a "pit"
       with bloody floors. To your left is a balcony from which you can deal with
       a few demons, most notably 2 Lost Souls. There's a lot of Hell Razers,
       Imps, and Revenants, as well as 2 Hell Knights and a Mancubus at the end
       of the fight (the Mancubus only spawns as you approach the waypoint).
    
       In the pit, there's a tunnel with many small armor and a Haste Powerup.
    
    Mission 6: Rune Challenge: "Seek and Destroy"
    
       After the fight a tunnel opens to the RUNE CHALLENGE 6.2.
    
    Mission 6: Extracurricular Activities around the second pit
    
       You can continue up the stairs for the main campaign path, or you can
       return to the levels entrance and look for two small adjacent caves that
       opened up.
    
       The right-hand cave has a suit of armor and an Automap.
    
       The left-hand cave has a green teleporter to a treasure room of sorts with
       CODEX ENTRY "Artifacts / Slayer's Testament #2". You could teleport back,
       but instead look for the exit corridor and find another CODEX ENTRY
       "Environments / Kadingir Sanctum" and ELITE GUARD 6.3.
    
       Finish the detour by following the corridor and using the yellow lift to
       cross the chasm. If you go straight, then left, you should see the stairs
       leading down to Rune Challenge #2 (and a suit of armor).
    
       Descend the stairs about halfway (above the decorative gate) and look for
       a ledge to the left you can jump onto to find SECRET 6.3, COLLECTIBLE 6.2:
       "Mancubus Model, Redguy".
    
       Back at the top of the stairs, find a FIELD DRONE 6.1 (now's time to get
       the Gauss Cannon's Siege Mode) and CODEX ENTRY "Artifacts / Doom Marine".
    
       A few stray small armor mark the top of a steep staircase. Descend it to
       see a holographic replay of Dr Hayden and some guards.
    
       POINT OF NO RETURN: Once you go through the gate ahead, you will no longer
       to able to get back to the earlier parts of the level.
    
       Pass through the gate (it'll open for you), into a fight scene.
    
    Mission 6: Fight: Hell Barons in Arena with two Subarenas
    
       The fight is already underway between the first Hell Baron and a bunch of
       the Possessed and 6? Imps. By far, the Gauss Cannon in Siege Mode is the
       easiest way to deal with the Hell Baron, then deal with the stragglers
       however you want.
    
       At some point, a Summoner appears. I usually use the Rocket Launcher, but
       Gauss Cannon or even Chainsaw works.
    
       Another Hell Baron and some Imps arrive.
    
       After that's all gone 6? Lost Souls spawn. It is good to take shelter in
       the more protected subarena and pick them off with the Assault Rifle or
       Shotgun or whatever.
    
       Finally, 2 Hell Barons spawn. I use the Quad Powerup and the Super
       Shotgun. If you already used the Quad Powerup, just keep moving and
       dodging their shots (they move fast, though) and use either the Gauss
       Cannon (you need to move fast, so no Siege Mode) or Super Shotgun.
    
    Mission 6: Onward, after a short Secret Detour
    
       OK, go back to the large main arena from the last fight. There is a big
       cave. Inside the cave (which can be a bit dark) is a lever: an Original
       Doom Level trigger. The location of SECRET 6.6, CLASSIC MAP 6.1 "Doom -
       Slough of Despair" itself is on the lower floor closer to where you
       entered the arena, or simple walk off the ledge between the two subarenas,
       and drop down.
    
       Or use the map: it looks quite distinct with a visible arrow drawn into
       the map in the Dossier. Once there, the arrow marks the correct switch to
       press (ie the Left switch). It accesses a Mega Health Bonus (although
       crudely rendered, it is just as effective as a modern-looking one).
    
       Go back to the subarena that once held the Quad Powerup, and now should be
       decorated with a glowing green circular symbol. When you approach the
       door, it will open.
    
    Mission 6: Fight: some small easy fights
    
       First, there's about 6 Unwilling in this corridor. they are useful for
       Weapon Upgrade Challenges (eg Tactical Scope, Heat Blast, Super Shotgun,
       Pistol). And 2 Lost Souls to watch out for.
    
       Instead of charging out island-hopping, turn right, and go up some stairs
       to overlook a Mancubus and 2 Revenants fighting. Help them kill each other
       with a suitable weapon (ie Rocket Launch or Gauss Cannon).
    
       Go ahead and island-hop over to the largest platform which should have
       some shotgun ammo. Turning left, 2 Cacodaemons will appear: kill them
       (using e.g. the rocket launcher). Go to the edge where the Cacodaemons
       appeared, and look across the chasm to see that a few islands connect you
       to another dilapidated staircase across the way. Make your way over. The
       landing hand a few small health, CODEX ENTRY "Monsters / Mancubus" and
       Gas.
    
       3 Unwilling and a Mancubus guard another tunnel: you should get a
       Checkpoint here.
    
       Continue up some stairs, to find 4 more Unwilling wandering around some
       armor: good target fodder.
    
       A CODEX ENTRY "Artifacts / Slayer's Testament #3" is found.
    
       The last easy fight is about 5 Imps fighting 10 Unwilling. (I like to work
       on the Savagery Rune and the Seek and Destroy Rune for this easy fight).
    
       Don't miss ELITE GUARD 6.4 here! (to the left from the way you entered)
    
       Enter a well-stocked tunnel ending with CODEX ENTRY "UAC Personnel /
       Olivia Pierce" for a Checkpoint preceding the final fight of the mission.
    
    Mission 6: Fight: Finale
    
       It comes in unseparated waves:
    
         * 4? Imps and 3? Hell Razers
         * 2 Hell Knights
         * 4 Revenants
         * 3 Mancubi
         * 2 Hell Barons and 1 Mancubus
    
       I tend to save the Quad Powerup and for the end; get the Armor on the
       toplevel (a sometimes overlooked location) early on to make it easier.
       Keep on the move and kill quickly.
    
       Walk up the hill to a holographic replay of some sort of ritual with a
       casket.
    
       Interact with the screen ??? to exit the level.
    
                 Mission 7: Argent Facility (Destroyed) "Hell on Mars"
    
       Notes on Combat Challenges:
    
         * Skeet Shot: Revenants fly into the air periodically to target you, and
           so the challenge isn't so much shooting them as killing them (they can
           take a lot of damage). Gauss Cannon/Siege Mode will reliably kill them
           in one hit; Rocket Launcher/Lock-On will reliably kill them in two
           hits. So these are my favorite weapons for this challenge.
         * Close Encounters: there's a fair amount of gas in this level, but it
           can be easy to forget to use the Chainsaw. Note that it can be best
           just to mostly fulfill the challenge on some easier demons, since they
           take much less fuel.
         * Knowledge is Power: easy
    
    Mission 7: Introduction
    
       Pick up CODEX ENTRY "Monsters / Barons of Hell"
    
       Go ahead and exit to the outdoor walkway, turning right (since left is
       blocked by fire).
    
    Mission 7: Fight: One Cacodaemon on Walkway
    
       Be surprised by a Cacodaemon; it's a bit annoying on this narrow walkway-
       with timing you can get it in one Gauss Siege Cannon, but one have space
       to dodge it as well.
    
    Mission 7: Getting back into Argent Facility
    
       At the end of the walkway, turn around and look for a walkway to jump up
       to. Next, jump across to a train and follow it to a small landing with two
       tarp-covered crates. Behind these crates is a lever for the Original Doom
       Level. After actuating the lever, drop down to another walkway/landing
       with a grated floor, and turn around to see a large octagonal pillar with
       a large "1" on it. Behind this pillar is SECRET 7.6, "Classic Level / Doom
       2: Underhalls".
    
       Immediately upon exiting this area, turn right, to see a right-dirt
       floored alcove with some crates. There is SECRET 7.4, COLLECTIBLE 7.1,
       "Cacodaemon Model / Rageguy". There's also some armor and Gas.
    
       Now, jump your way up to the highest accessible walkway.
    
       You'll get a Checkpoint shortly before a long double-jump. It's not really
       difficult though. Continue until you are looking into a damaged corridor
       which crosses the chasm.
    
       Drop into the hallway through the gaping hole in its roof. Turn around to
       find an ELITE GUARD 7.1 (along with some armor and shotgun ammo).
    
       Go forward to the computer area. Find CODEX ENTRY "Environments / Argent
       Facility".
    
       Interact with the computer for a 48 second cut scene, whose immediate
       consequence is that you need a yellow keycard. A marker will take you to
       the airlock, which has a screen you can interact with.
    
    Mission 7: Fight: Side Cargo Bay Exterior
    
       While you may not see monsters immediately, they are just to the right: a
       Hell Razer, a Possessed Engineer, and 6? The Possessed. You can take care
       of many by shooting the barrel. Expect 2 more Revenants, Imps, Possessed
       Soldiers, 2 Cacodaemons, and a Hell Knight.
    
    Mission 7: Fight: Maintenance Exterior
    
       Drop down to another former gore nest location, near the large Union
       Aerospace tank, on a ground area with lots of fire, to get another small
       fight with Imps, Hell Razers and a Hell Knight.
    
       There is a Hologram device near some ammo.
    
       Look down into the next area. This is the area that used to have a blue
       Force Field, but now just has some fires. You should see the pale-orange
       glow of a Berserk Powerup. Drop down.
    
    Mission 7: Fight: Main Cargo Bay
    
       First to appear will be 2 Cacodaemons and 1 Imp. One Cacodaemon often
       starts very low and can be chainsawed to solve several problems at once.
    
       After that, Imps, 3? Revenants, and a Summoner appear.
    
       In fact, the Berserk may outlast the fight: you can perhaps even you it to
       kill some stuff in an adjacent area.
    
    Mission 7: Fight: Main Cargo Bay Adjacent: old platform area
    
       This area is easily skipped.
    
       There's a Hell Knight and a few Imps.
    
    Mission 7: Fight: Main Cargo Bay Adjacent: through tunnel
    
       This area is easily skipped.
    
       A Hell Knight, a Hell Razer and at least 1 Imp.
    
       This is the area that had the Lever for the classic doom secret in Mission
       4.
    
    Mission 7: Accessing Rune Challenge "In-Flight Mobility"
    
       From the Old Platform Area, there's a blue lift that'll drop you on the
       rock for this Rune, RUNE CHALLENGE 7.1.
    
       Or, you can jump across from the cargo crates in front of the Security
       Station Doors.
    
       NOTE: This challenge is frustrating for many people, since it has little
       margin for error. However, it is worth the practice, because the Rune is
       critical for some of the bosses.
    
       From this location, you can drop down SECRET 7.2 which has a Mega Health
       and ELITE GUARD 7.2. Equip the In-Flight Mobility Rune (which you just
       got). Go to the edge of the rock with the chasm and go to the edge of the
       rock. Turn around so that so can drop backward off the rock and face into
       it. Walk backward and fell to a cave, jumping forward right as you see it,
       so that you'll land on the Mega Health. The Elite Guard is in the shaft
       behind it. To get back, jump to a rock with a blue booster.
    
    Mission 7: Fight: Security Station
    
       To get here, from the Main Cargo Bay, look for a pile of 3 crates to climb
       on. The door should have a marker on it (an in-game destination) and there
       should be Gas here.
    
       Entering, there's even more supplies littered throughout a gory hallway.
    
       Interact with the door to get a short cut-scene introducing us to the
       Pinky.
    
       The fight begins with 2 Pinkies and at least 1 Possessed Soldier (and a
       hard-to-count number of The Possessed in the peripheries- most of these
       get killed by other demons!).
    
       After killing those Pinkies, another wave of 4? Pinkies (etc) is
       triggered.
    
       After the fight, visit the Auto-Map, and get the CODEX ENTRY "UAC
       Personnel / Dr Samuel Hayden 2".
    
       There's also a Health Station here.
    
       After triggering and watching a holographic replay, you'll be allowed out
       the Security Station's second door.
    
    Mission 7: Fight: Exiting Security Station
    
       Opening the door, you'll see a Pinky: but there's actually 2 Pinkies. As
       well as 2 Revenants, 2 Imps. You can use the Quad Power-Up but I usually
       save it for the more tough fight coming up. Once you kill all these guys
       you'll get a CHECKPOINT.
    
       There's ELITE GUARD 7.3 on the top level.
    
       Interact with the Munitions Crate in the far corner of the lower-level.
       Unfortunately you'll need to re-do this each time you die: on the positive
       side, this Munitions Crate refills between most battles.
    
    Mission 7: Fight: Exiting Security Station and Entering ???
    
       This fight is triggered when you take the stairs across the chasm after
       killing everyone.
    
       Initially there just a lot of The Possesseds staggering around, but a
       Revenant, an Imp, and a Cacodaemon are the first wave of guests to this
       party.
    
       A second wave (somewhat indistinct), is another Revenant, Cacodaemon and a
       few Imps.
    
       The third wave is different: two Pinkies and a Mancubus. These guys come
       out of the hangar ahead of you, and if you time it right, you can take
       them out with a single satisfying Quad-Damage Siege Cannon on the bridge.
    
    Mission 7: Fight: Indoor Gore Nest
    
       Enter the building picking up health, Gas, Plasma, and CODEX ENTRY
       "Monsters / Mancubus 3".
    
       Almost the entire pre-fight can be handled with a single Gauss Cannon
       Siege Mode shot. Except you may have to deal with a pernicious Hell Razer,
       plus a lurking Possessed Security (use the Gauss Cannon on this fool, who
       hides on the left as you approach the Nest).
    
       Before destroying the Gore Nest:
    
         * Consider taking the Megahealth Powerup on the crate above.
         * You'll probably want to use your chainsaw, so find Gas where the
           Possessed Security hides (to the left as you initially walk toward the
           Gore Nest).
         * The two Pinkies spawn in reliable locations, one near the entrance
         * I usually retreat toward the entrance to minimize complications and
           environmental risks: your mileage may vary.
    
       In addition to 2 Pinkies, a Hell Knight and a few Hell Razers spawn.
    
       The finale is a Hell Baron, who starts on the far side of the room (with
       the Health Station and chainsaw). I like to use the chainsaw on it, but
       the Gauss Cannon/Siege Mode is also quite effective.
    
    Mission 7: Post-Fight ??? Cleanup
    
       Pickup all you can.
    
       There should be a screen prompting "Reset Crane to Base?" to access near
       the bridge over the electrically charged floor. Actuating the Crane will
       cause a large suspended block to move within jumping range. Jump onto it,
       then jump right onto a catwalk. This is SECRET 7.5: access FIELD DRONE 7.1
       at the end of the U-shaped catwalk. (I tend to choose Chain Gun / Mobile
       Turret here.)
    
       Exit through the door near the Health Station.
    
    Mission 7: Accessing Rune Challenge: Armored Offensive
    
       Exit the building and turn left, killing an Imp and Revenant.
    
       Jump across to the right and follow the walkway to the end to find RUNE
       CHALLENGE 7.2 "Armored Offensive" (which is also SECRET 7.3).
    
       This is a useful Rune for hard fights, since getting more armor is the
       same as more health, for the most part.
    
       Now, turn around, and run back toward the waypoint. To the left you'll
       find a Munitions Crate on a plateau. Often there are The Possesseds
       stumbling around and even a Cacodaemon at times. After killing all that,
       you should find a CHECKPOINT.
    
    Mission 7: Fight: Upper Gore Nest
    
       Continue along the ledge, jumping around to the green-lit ledges. At the
       top, you'll find an airship with some loot - including CODEX ENTRY
       "Monsters / Cacodaemon", a Hell Knight, a few Imps, and a bunch of
       Possessed worshipping the Nest.
    
       Kill the Hell Knight and the Imps, and use the Possesseds for target
       practice.
    
       When ready, destroy the Gore Nest.
    
       Immediately a Hell Knight will spawn behind you, and some Imps and Hell
       Razers.
    
       There will be 3 Cacodaemons and 3 Revenants over the course of the battle
       as well.
    
       Toward the end of the battle, a Mancubus will emerge.
    
       Use the Haste Powerup in the corner whenever you need a boost: this fight
       isn't too tough.
    
    Mission 7: Post Upper Gore Nest
    
       ARGENT CELL 7.1: Looking back the way you came, you should see a plateau
       at your elevation: it is easy to get to. Once there, look down at see the
       Argent Cell: drop down to it and choose your powerup.
    
       Go back to the site of the Gore Nest, and enter the door.
    
       There is a Pinkie Corpse holding the Yellow Guard Corpse. You can interact
       with it to get the Keycard.
    
       There's also a secret here. Look up for a bloody ledge in the ceiling at
       the left of the room on entry. Find SECRET 7.1, COLLECTIBLE 7.2, "Baron of
       Hell Model, Patriotguy".
    
       Return to get the Yellow Keycard, watch the holographic replay, and use
       the Yellow Door.
    
       Drop down the elevator shaft. Before exiting the obvious way, turn around
       and look up to find a square duct: jump into it and find ELITE GUARD 7.4.
    
       Exit the elevator shaft: you should recognize this as the site of an
       earlier Gore Nest battle. Make a hairpin turn to the right and go in the
       Yellow Keycard Door.
    
    Mission 7: Fight: Tram Access
    
       A few Possessed Soldiers and a number of The Possessed lurk here, useful
       for some Weapon Upgrade tasks. When ready, interact with the Tram Console
       to "Resume Route" to finish the level.
    
               Mission 8: Advanced Resource Complex "A Brighter Tomorrow"
    
       Notes on Combat Challenges:
    
         * Bottle Opener: quite easy as there's a lot of The Possesseds wandering
           around in non-threatening situations
         * Double Take: watch out! you can't do this in replay if you miss a
           Rune!
         * Hide and Seek: easy
    
    Mission 8: Introductory Lobby (with small Fight)
    
       Enter a large lobby area, finding a Mancubus killing some The Possesseds.
       After killing these, look for a pair of restrooms. In the Men's Restroom
       is some armor you can save for later maybe.
    
       In the Woman's Restroom is a hatch allowing access to a secret area. Climb
       onto the sinks and look around for the bloody hatch: jump to it and follow
       the duct (there's Gas) to drop into a room (SECRET 8.7) with an Auto-Map
       and an ELITE GUARD 8.1. The screen next to the door will open it.
    
       After exiting the Secret Room, you'll enter a Security Area with 6? The
       Possesseds, a Health Station, an ARGENT CELL 8.1, a Plasma Gun, and a
       terminal to Release the Safety Lockdown: do that.
    
    Mission 8: Fight: Main Lobby
    
       Exiting the security area, there's a handful of The Possessed to dispatch.
       Then a Possessed Soldier or two, and finally a Possessed Security and a
       Hell Knight in the main lobby area. Keep moving and focus on the meaner
       demons.
    
       Watch a holographic replay of Dr Hayden and Olivia Pierce arguing about
       her research. Meanwhile, pick up CODEX ENTRY "Environments / Advanced
       Research Complex 2" from the main desk. When you interact with the panel
       to open the main building, there will be a Checkpoint, so gather supplies
       before that - the upcoming fight can be a bit difficult.
    
    Mission 8: Fight: Central Area of ARC
    
       The entryway contains 6 Imps worshipping or something. Use a grenade or
       whatever you need for weapon or rune upgrades.
    
       Drop down to the lower central area, where you'll find 6-8? The Possesseds
       worshipping a Gore Nest. Often, an Imp for above will escape and find you
       as you are down here: watch out!
    
       My strategy for the start of this fight: Destroy the Gore Nest; lob a
       grenade into the center where Imps are forming in front of you (this tends
       to be quite effective), do a U-Turn to find 2 Imps to blow away with Super
       Shotgun. A Mancubus has formed in the tunnel to your left: kill it with
       whatever means, including Chainsaw (there's more fuel in the central area
       near the Gore Nest's location).
    
       Once the Summoner comes into existence, grab the Berserk Powerup. In a mad
       rage you'll likely be able to kill nearly all the remaining demons, but
       focus on the hard to kill demons just in case, as possible.
    
    Mission 8: Meeting Dr Hayden
    
       All the bad guys being dispatched, follow the in-game waypoint to Dr
       Samuel Hayden's office.
    
       POINT OF NO RETURN: You can't come back here, so if you are missing the
       Auto-Map or the Elite Guard, get them now. (??? check that they're even
       still available post-fight?)
    
       Dr Hayden will resupply you to a large extent (he could really use a Mega
       Health but whatever). He will also explain about the "Helix Stone" and Dr
       Pierce's private lab "across the chasm". Finally he directs you to the
       service elevator: classy.
    
       The Dr is in no mood for futher conversation, so take the service
       elevator. When the door opens, find CODEX ENTRY "UAC Personnel / Dr Samuel
       Hayden 3".
    
    Mission 8: Moxim Service Bay
    
       The olive green area has 4? The Possesseds. Kill them and find ELITE GUARD
       8.2 in this area.
    
       Continue along to get charged by a Possessed Engineer.
    
    Mission 8: Fight: Gore Nest 1
    
       This fight takes place in a small-ish pit area. There's a Haste Powerup.
    
       The pre-fight is all Possessed Engineers and is unlikely to be a problem.
       Often they materialize rather late anyways. ???
    
       The initially a Cyber-Mancubus appears in front of you; then 2 Mancubi;
       then another Cyber-Mancubus; along with 6? Imps.
    
    Mission 8: After Gore Nest 1: Secrets Galore
    
       Go to the marker indicated by the game, and interact with the screen to
       "Lower Security Field".
    
       First, there's the RUNE CHALLENGE 8.1 (SECRET 8.8). Look out onto the big
       chasm and turn 90 degrees left to find an airlock. Use it to access Rune
       Trial "Blood Fueled" (I personally don't use this one). There also a suit
       of armor.
    
       Second, there's the Classic Doom Level, SECRET 8.10. This jump to the
       lever is pretty tricky.
       Jump across to the immediate platform, and turn left and drop onto the
       platform below the Gas can. Turn around and look to the left to see a
       green light-bar, indicating a platform you can jump to. Keep going around
       this rock and jumping up: the top has a suit of armor on it. From this
       top, look directly opposite from the entrance area. You should see some
       pipes and a lever at your exact elevation: you need to jump there. The
       trick is that there is an invisible ledge about 12' (4 meters) below the
       level. If you land on that it is confusing: but if you have the In-Flight
       Mobility Rune you should easily be able to jump from this awkward position
       to the Lever.
    
       Third, from the Lever, face the piping and jump onto the pipe. Duck and
       turn into the cave, and search around into you find SECRET 8.6,
       COLLECTIBLE 8.1, "Supershotgun Model / Phobosguy"
    
       From there, look out for Lost Souls, and jump around until you get where
       they suit of armor was (on top of the rock). From there, jump back toward
       the entrance, and keep going that direction to find the Classic Doom Level
       (SECRET 8.10)
    
       Fourth, go, yet again, to the high point where the suit of armor was. Look
       for a lower pinnacle and jump there. From there, it is about a 45-degree
       right-turn to the Mega Health Powerup, SECRET 8.5. Once you get this
       powerup, a Cacodaemon will rise to attack you.
    
       Fifth, from where the Cacodaemon appeared, look for a bay opening. It
       contains an ARGENT CELL 8.1, SECRET 8.4.
    
       Finally, look for a hatch that is opening and closing (the in-game
       waypoint should lead you here). Jump down onto it for an irreversible
       Checkpoint.
    
    Mission 8: Twin Intake Area
    
       Here we are in a pair of air intakes. If you look around you should see a
       Field Drone behind a grate: it is actually in the space directly in
       between the twin intakes. But it must be accessed from the other side.
       Jump onto one of the rectangular panels, and jump onto the only walkway.
       You should see a green-lit hatch to jump to. We want to get to the top of
       the air intake: we could do it here, but we should access the Field Drone
       first.
    
       So, walk through the tunnel: an Imp will jump out.
    
       Keep going: you'll get to the other intake. Turn it off using the panel,
       and jump down the hatch (just like the one you came up). You should find a
       shaft with FIELD DRONE 8.1 in it.
    
       Reverse your steps, and turn the air intake back on. Step in, and even the
       ride up!
    
       Climbing up you'll get to a 4-way shaft intersection: directly in front
       and in back of you are each of the twin intakes. The in-game waypoint
       points you toward BFG Labs Lobby. The other direction has some armor if
       you need it.
    
       Proceed toward the in-game waypoint, to a lobby. This area has TWO green
       door: the big one directly in front of you with the waypoint, and a
       smaller door to the left housing SECRET 8.3: ELITE GUARD 8.3.
    
    Mission 8: Fight: The BFG Labs Access Hallway
    
       Now, go forward into the ring of labs in the BFG complex. Get a big gun
       out and shoot 5 Possessed Soldiers, 2 Possessed Securities, and 1
       Cyber-Mancubus.
    
       I usually use a super-shotgun to start, then a mix of rockets and gauss
       cannon to finish the Cyber-Mancubus.
    
    Mission 8: Notes on the BFG Labs
    
       Let's look at the labs on the outside of the hallway-ring.
    
       I'm going to go clockwise (as seen from above) starting at the Yellow
       Door.
    
         * Yellow Door: find a Torso whose retina will grant you access to the
           BFG itself
         * Bluish Door "Prototype Lab 02". 4 The Possesseds.
         * Red-lit Door-ish area: there's a corpse, a Gauss Cannon and some
           plasma fuel.
         * Bluish Door "Prototype Lab 01". 4 The Possesseds. Once these guys are
           dead, stand on the machinery and look for an open duct. SECRET 8.2,
           COLLECTIBLE 8.2: "Pinky Model: Pinkguy" ??? Follow the duct to drop
           into a room with a The Possessed, plus CODEX ENTRY "Weapons /
           BFG-9000". Go out this door into the main circular hall
    
       That's it: now go to the in-game waypoint and interact with it.
    
       You can probably figure out how to get the BFG from here, but the next
       section will spare no details.
    
    Mission 8: Accessing the BFG (Defeating the Security Measure)
    
       Enter the chamber; the alarm will sound, i guess it noticed that the
       retina was attached to a corpse. Anyways, jump onto any of the symmetric
       metal platforms, and watch the crazy security apparatus.
    
       After about 10 seconds, a sequence of lamps will light up and ypu can to
       shoot the obvious cells (you need to shoot 4 of the 6 cells). Do so, and
       the security system collapses and you can claim the BFG for your arsenal.
    
       Watch the cut-scene.
    
    Mission 8: Fight: Test The BFG
    
       This fight is designed to be a nice place to use the BFG, for casual
       players. But it's probably better to work on all kinds of Weapon Upgrades
       (Super Shotgun, Gauss Cannon-Siege Mode, Chain Gun-Mobile Turret).
    
    Mission 8: Before heading out ???: Rune Challenge "Intimacy is Best"
    
       Watch the holographic replay.
    
       Before going ahead, go right through a newly green-lit door; turn left
       into a yellow-gold-lit narrow opening to SECREt 8.9, RUNE CHALLENGE 8.2
       "Intimacy is Best"
    
    Mission 8: Gore Nest 2
    
       Now, charge forward into a battle designed to showcase the BFG (and you
       may as well use it, since you can only store 3 charges.
    
       Prefight: use a few Siege Mode/Gauss Cannons to kill the incoming hordes
       from the Checkpoint. After that, coming into this area, 3 Lost Souls will
       spawn: one straight in front, one left, one right. After you learn where
       they spawn they are easy to deal with - and since you have to re-kill them
       every time you die in this battle, you'll probably learn where they spawn
       too.
    
       Now, destroy the Gore Nest. Use the most powerful weapons available.
    
       When you think you are done, it's a bit of a trap. You have NOT gotten to
       a Checkpoint until you kill the 2 Hell Barons that follow.
    
       A robotic voice will announce that the demonic threat level is reduced,
       but that is just a temporary reprieve: not a Checkpoint.
    
       However, one easy BFG blast will take care of both Hell Barons.
    
       To conclude the level, enter the elevator and "Exit Facility".
    
                           Mission 9: Lazarus Labs "Lazarus"
    
       Notes on Combat Challenges:
    
         * Variety is the Spice of Death II: note that glory kills on Hell Razers
           count as well.
         * Thread the Needle: use the BFG. There's two fights shortly after
           acquiring it that should reliably achieve this.
         * Time Well Spent: easy, but also easy to miss. Make sure you do it
           before leaving Olivia's back lab.
    
    Mission 9: Intro
    
       Grab Gas, the CODEX ENTRY "Environments / Lazarus Labs", and recharge your
       health (you can't get back here). In the next room you can get the rarely
       used Siphon Grenade. Then jump down the chute.
    
       Following the waypoint, you'll remove a corpse-chunk that's blocking the
       elevator, and 3 Imps will jump out. Kill them, then use the Munitions
       Crate. The non-Secret flow is to jump into the shaft and open a grate.
       Instead, look behind the crates behind the Munitions Crate. There's a duct
       (SECRET 9.1): follow it to a Mega Health that'll drop you into the next
       fight.
    
    Mission 9: Fight: First Warehouse
    
       A big fight, with many Hell Knights and Revenants.
    
       Kill all these guys, and enter the green-lit doorway.
    
    Mission 9: More Secrets
    
       Go up some stairs in a red-lit area. Before continuing on, turn around to
       see a duct with shotgun ammo. Jump into the duct, and follow it to a
       grate, that you must interact with. Enter SECRET 9.5. Here is ELITE GUARD
       9.1 and CODEX ENTRY "Database / Elite Guard 2".
    
       Now, continue toward the in-game waypoint. You'll pass through a
       transparent walkway while Dr Hayden tries to explain things. There's lots
       of activity outside.
    
       At the end of this walkway, find FIELD DRONE 9.1 (probably unnecessary if
       you have used most of the Field Drones up to this point).
    
       You'll find yourself in a curving hallway with 4 The Possesseds, and CODEX
       ENTRY "Monsters / Cyberdaemon 2".
    
       Continue down the hall to a few Possessed Soldiers and a Hell Knight.
    
       Continue up a short flight of stairs and look for a white hatch in the
       floor right in front of you. Interact with it to drop with for SECRET 9.2.
       Climb up to find RUNE CHALLENGE 9.1 "Rich Get Richer".
    
       When done, actuate the screen near the door to exit - you'll be back at
       the hatch.
    
       From the hatch, go into the next room: there should be two large steamy
       windows in this relatively small area. Facing the windows (as you come
       into the room), look right for a torn duct you can climb into. Drop down
       into an area with the AUTO-MAP. Exit through a duct behind the columnar
       structure in the room. You'll come to an old school looking panel of
       lights. Jump up, and look for a grating to open, to exit back to an early
       hall.
    
    Mission 9: Fight: Miscellaneous Hallway Guards
    
       The first room has a few Possessed Securities and many The Possesseds and
       a couple of Possessed Engineers.
    
       The second room has a CHECKPOINT (used for the next fight) and 4 Possessed
       Soldiers and a Hell-Razer. The next room has a bunch of ammo and a Health
       Station, then drop down the hatch to enter the next fight.
    
       POINT OF NO RETURN: Once you finish the next fight, you cannot get back to
       this tunnel area (so make sure you interacts with Rich Get Richer, even if
       you didn't solve it)
    
    Mission 9: Fight: Mancubus Operating Room
    
       Many Possessed Securities, The Possessed, Hell Razers, Possessed Solders,
       3 Mancubi will spawn. Toward the end of the fight is 2 Hell Knights. I
       like using the Plasma Rifle Heat Wave with the Quad Damage to plow through
       the bad guys - but your mileage may vary.
    
       After the fight look at the empty mancubus bed at the back of the room,
       between the two exit doors. Behind this, is a screen you can actuate to
       find ELITE GUARD 9.2 in SECRET 9.4.
    
    Mission 9: Fight: Stone Tablet Exhibit Hall
    
       There's a Munitions Crate in the entrance hallway to this area. Once
       you've looted the area, look through the door to see if you're going to be
       ambushed by a Possessed Soldier right next to the entrance. Open the door.
    
       This fight begins with 3? Possessed Soldiers (one is close-by and needs to
       be dealt with urgently) and a large number of The Possesseds (use a
       grenade or two maybe). Shortly, 2 Pinkies spawn at the back of the room.
    
       Killing those Pinkies will cause the spawning of 4 more Pinkies and a bevy
       of Imps. Use the BFG, Chainsaw, and general evasive maneuvering.
    
       Cheap Strategy: After killing the Possessed Soldiers, go into the tunnels
       behind the stone artifacts. The monsters (most conveniently, the Pinkies)
       cannot go back there, but Imps can still fireball you. You may need to
       chainsaw someone for ammo: the second Pinkie can be a good choice.
    
       Post-Fight: Going back to the entrance door of the room, and look at the
       stone tablet to your left. There is a gap you can use to enter some access
       tunnels: this is SECRET 9.3. In the back, find COLLECTIBLE 9.1 "Olivia
       Pierce Model, Eliteguy".
    
       There's also a Mega-Health you should take before leaving the backstage
       area. (Hint: equip Rich Get Richer before taking the health to get one of
       the Upgrades)
    
       Cheap Strategy: If you want to get the Rich Get Richer upgrade in an easy
       but slightly repetitive way, do NOT get the Mega Health before opening the
       door. Instead, open the door, getting a checkpoint. Then, grab the Mega
       Health (with Rich Get Richer equipped, obviously), and commit suicide
       (shoot the ground next to you repeatedly with the Rocket Launcher). When
       you revive, you'll have to open the gate again, then repeat (starting with
       grabbing the Mega Health). Repeat as many times as you like- you'll
       probably only get 3 more before Mission 13, which is where it is really
       useful.
    
       Press the screen as indicated by the in-game waypoint. Enter what looks
       like an elevator to transfer you to the Lazarus Archives.
    
    Mission 9: Accessing the Helix Stone
    
       This really just involves interacting with a few screens, in all cases,
       the in-game waypoint takes you there.
    
       SECRET 9.6, COLLECTIBLE 9.2 "Samuel Hayden Model, Toxicguy" is found in
       the circular archive room. Look on the upper floor for a red display
       screen (there's another similar display in a cyan color: ignore it).
       Behind it, a single archive cell's light is red -- all the other lights
       are yellow. Interact with this to obtain the doll.
    
       The anteroom to Olivia's Lab holds CODEX ENTRY "UAC Personnel / Olivia
       Pierce".
    
       After a few screens, you be in Olivia's Private Lab: there's a central
       hologram of a stone coffin-like thing being guarded. There's BFG Ammo, a
       Munitions Crate, an ARGENT CELL 9.1, and a screen to interact with. On the
       left is a lone dilapidated computer where Demon Destruction can be
       "played": just interact with the running computer on the side and exit to
       get the Combat Challenge.
    
       The final screen is back in the circular archive room: be ready for a
       fight after Dr Hayden rambles on a while.
    
    Mission 9: Fight: Circular Archive Room
    
       Be prepared for a endless Imps and a long sequence of Hell Knights. An
       Mancubus will spawn; and toward the end, 2? Cacodaemons.
    
       After dispensing with all the demons, a circular stairway drops down from
       the center of the room.
    
    Mission 9: Fight: Small fight in Bloody Temple / Pew Area
    
       A few Possessed Securities and a bunch of The Possesseds linger about this
       gory area.
    
       When cleared, there will be a hologram of Olivia watching over a
       ritualistic sacrifice.
    
       There's armor behind you as you stand in the entranceway to this area.
    
    Mission 9: ???
    
       Exit to the right to a blood-strewn corridor with books and candles.
    
       You will get to a circular room with a pit in the center. Looking in, you
       can see an Elite Guard, but before that, look right for a Lever to access
       a Classic Map.
    
       Now, jump in (SECRET 9.7) and get ELITE GUARD 9.3 and SECRET 9.8, CLASSIC
       MAP 8.1 "Doom - Tower of Babel".
    
       Jump back out, and go to the screen with the waypoint: "Cycle Hatch".
    
       Do this, and jump onto the platform while is plugging the hole. Wait for
       it to lift you up, like an elevator.
    
       Drop down, and keep going and you'll get to a yellow-lit door labeled
       "Maintenance Only". Enter for a fight.
    
    Mission 9: Fight: Server Hall
    
       You catch a few Possessed Securities off-guard, use grenades etc. There's
       also a Pinkie ahead of you in the hallway. And a few more The Possesseds -
       including some that may surprise you by popping up.
    
    Mission 9: Server Hall
    
       The hallway become increasingly bloody, and you finally open a door onto a
       console area. A hologram with Olivia is playing, and you must interact
       with a terminal at the waypoint here, the energy refractor control. It
       opens the twin doors.
    
    Mission 9: Fight: Two Level Lounges
    
       Two identical hallways take you to a symmetric 2-level area strewn with
       Imps, Possessed Soldiers but mostly The Possessed.
    
       Once cleared, from the entry, go to the lounge on the right on the
       upper-floor. Look around for a bloody duct at approximately head-height.
       It takes you to SECRET 9.9, RUNE CHALLENGE 9.2, "Saving Throw".
    
       There's also ELITE GUARD 9.4. Outside the door, in the non-secret area, is
       a Munitions Crate.
    
       Then go to the waypoint: a large silo with green concentric circles
       surrounding the waypoint itself.
    
    Mission 9: Portal Area Fight
    
       The robotic voice announces demonic presence, but you won't see much. You
       have to enter the narrow hallway and go through the teleporter.
    
       Before doing so, equip In-Flight Mobility. Then enter the teleporter and
       jump back. You should land on a shelf instead of falling to the ground.
       This is the perfect place to use the BFG to get the Thread The Needle
       Combat Challenge: it'll make the fight much easier too.
    
       This is a good fight to use the Plasma Gun / Heat Blast - fight everyone -
       grabbing the Haste Powerup whenever you need health. Use another BFG if
       helpful - there's a few lying around. When the Pinkie or Hell Knights show
       up, grab the Quad Powerup: it (along with Heat Blast) should be easy work
       of the remaining heaps of demons.
    
    Mission 9: Prepare for Boss fight
    
       Follow waypoints, grabbing supplies, along with CODEX ENTRY "Monsters /
       Cyberdemon".
    
       Dr Hayden explains that this fight will have two parts. The first part is
       the easier one.
    
    Mission 9: Boss Fight, part 1: Mars
    
       Here's the most notable Cyberdemon moves for the first part:
    
         * the Rockets: he'll launch a volley of horizontal rockets; so long as
           you keep moving you should be ok.
         * the Charge: things will slow as he prepares to charge, so get ready to
           jump away.
         * the Jumpable Laser Shot: this thing does a lot of damage so you really
           need to jump over it.
         * the Charged Laser: this multiple beam laser shoot from his arm. It
           starts red and intensifies to whitish-yellow before firing. You really
           benefit from the In-Flight Mobility Rune for dodging this - upgraded
           is better.
         * the Mortar Volley: he will launch a bunch of rockets upward; their
           projected landing spots will be on the ground - find a place in
           between them to stand. This attack is combined with a Charge, a
           Jumpable Laser Shot, or a Changed Laser.
         * the Sidejump: he will sometimes take a big jump to the side. This is
           his (pretty effective) move against slow Gauss Cannon and BFG
           enthusiasts: don't waste your ammo if you detect it.
    
       Recommended Runes: Vacuum, Ammo Boost, In-Flight Mobility. (notes: Armored
       Offensive is useless since he doesn't drop armor. Saving Throw is
       marginal. Rich Get Richer is good if you have 100 armor (unlikely). He
       stays staggered for a while, so Dazed and Confused isn't really helpful.)
    
    Mission 9: Boss Fight, part 2: Hell
    
       A small cut-scene transports you to Hell; the Cyberdemon gives you the
       claw, and is reborn. You will also be pretty well charged up.
    
       He adds two new attacks to his repetoire:
    
         * the Triple Jumpable Laser Shot. The first shot will be low; the second
           high; and the third low. It just takes practice. Easy mistake:
           double-jumping the first laser and getting hit by the second.
         * the Double Wall. He makes a temporary corridor, which'll be combined
           with a Triple Jumpable Laser Shot or Rockets. To deal with the Double
           Wall with Rockets, move in a circular pattern using In-Flight
           Mobility.
    
       Same Rune Notes apply as above.
    
       Feel free to use all of your BFG ammo.
    
       When the fight is over, jump into the red teleporter.
    
                       Mission 10: Titan's Realm "Titan's Realm"
    
       Notes on Combat Challenges:
    
         * Trick Shot: I don't know why, but using the Rocket Launcher's Lock On
           mode seems to achieve this reliably. There are other ways, but I
           haven't found anything as consistent.
         * Atop the Mountain: there's a number of fights that end with the Hell
           Baron. For some reason, i often accidentally kill them instead of
           staggering them. You have to jump from higher ground to do this! This
           fight where you get the Blue Skull is probably the easiest to get this
           on, because the Hell Baron starts in a pit.
         * Dominator: there's a Berserk Powerup that is your main helper here.
    
    Mission 10: Introduction
    
       From the walkway, find CODEX ENTRY "Artifacts / Slayer's Testament #4".
    
    Mission 10: First Fight
    
       Jump far down to a bloody pit to be immediately attacked by 3 Cacodaemons.
       As proceed up the stairs to be attacked by another Cacodaemon and a
       Cyber-Mancubus.
    
       Continue up the hellish path to a yellowish cave guarded by 4 Lost Souls
       and 2 Cacodaemons.
    
       CHECKPOINT.
    
       Enter this room: you should see a bridge over a pool of toxic sludge. If
       you look under the bridge, you can see a Skull Switch. Actuate it and get
       out of the sludge. Facing into the room from the entrance, this caused an
       alcove to open up on the toxic floor, right next to a green torch. Inside
       this alcove is SECRET 10.3. ELITE GUARD 10.1. And some armor.
    
    Mission 10: Fight: Entrance Hallway
    
       Proceed, triggering the creation of some Lost Souls, some Hell Razers and
       a Pinkie.
    
       Proceed to the right. When you grab the suit of armor, it'll trigger 2
       Hell Knights to instantly appear. There are also 4 Unwilling in the next
       room, along with a Skull Switch: press it.
    
       This'll trigger the spawning of a Cyber-Mancubus, which will end this
       fight.
    
       CHECKPOINT.
    
       Now, pick up loot and search around for the FIELD DRONE 10.1, SECRET 10.2
       (it was visible before so it may be on the map).
    
       Proceed to the next fight: the target will be a gated-off green
       teleporter, but some demons will distract you en-route.
    
    Mission 10: Fight: First Teleporter
    
       Upon entry to this complicated arena, a Cyber-Mancubus will spawn off to
       your left, and a Mancubus will spawn in the area in front of you. Polish
       them off however is convenient.
    
       A gaggle of other daemons come along as well. A few Imps, few Revenants, 2
       Pinkies.
    
       Use the Haste since this is the only fight in this area - use it to work
       on the Dominator Combat Challenge.
    
       Once you get the CHECKPOINT, approach the Teleporter and the bars will
       lift. Enter for an iconic fight.
    
    Mission 10: Fight: Bloody Cave
    
       Dave's Opening: I usually turn right coming out of the Teleporter, picking
       up shutgun ammo and a suit of armor. Look left into a cave before a Yellow
       Lift: there should be Rockets on the ground and a Quad Powerup in the
       background. In a few seconds, a Mancubus will appear right on the rockets:
       lob some grenades and go up the stairs right past the Yellow Lift. You
       should find a Gas can, and down the hallway, the only Pinkie in this
       fight. Kill it and then run and fight as usual.
    
       The finale is 2 Hell Barons. I often save the Quad Powerup for them (note
       that 4 Imps spawn when you take the Powerup).
    
       Post Fight: the map may have a doll on it: SECRET 10.1, COLLECTIBLE 10.1
       "BFG-9000 Model / Keenguy". If not, it's in an alcove of the entrance
       wall.
    
       Follow the in-game waypoint to the teleporter. You'll arrive at the
       Auto-Map, use it.
    
    Mission 10: Fight: Rectangular Pit
    
       After 6 Lost Souls, deal with 4? Hell Razers and a bunch of Imps. They can
       be mostly killed just by shooting barrels. Use the Rocket Launcher on the
       Lost Souls to get the Trick Shot award or kill them however you want.
    
    Mission 10: The Yellow Skull and its Door
    
       Post fight: look for a Yellow Lift near the red door to get you onto the
       rafters. Across the way is a yellow pyre: jump to it for SECRET 10.4,
       COLLECTIBLE 10.2: "Cyberdemon Model, Silverguy". Jump back.
    
       Now jump over to the landing with the green suit of armor and a
       wood-grid-patterned door. It'll open and you can take the Yellow Skull.
    
       But! It's a trap. A very easy obvious trap. I think you'll figure it out.
    
       Continue through the hall (in the direction of the greenish area with the
       gibbet - the area you haven't been to yet).
    
       A grate will appear to block access to the yellow door.
    
       So, you must go left into a toxic area with a bunch of Unwilling
       staggering around. You will see an Invulnerability Powerup here, and at
       the end of the corridor, an ELITE GUARD 10.2 and a Skull Switch. Activate
       the Skull Switch.
    
    Mission 10: Fight: Toxic Sludge Area
    
       On return, two hatches will open exposing 2 Mancubi. You can use the
       Invulnerability on them, or fight more carefully and save it for a minute.
    
       Once they are gone, take the Invulnerability if you haven't and run up the
       stairs to fight 3 Pinkies.
    
       After that, the Yellow Skull Door is accessible, and a CHECKPOINT.
    
       Before going through the Yellow Door, though, note that another passage
       has opened and get ARGENT CELL 10.1 and CODEX ENTRY "Monster / Pinky".
    
    Mission 10: Fight: Pounding Rock Area
    
       The Yellow Skull Door opens to reveal what appears to be a red skull
       switch, but it's a trap: the floor drops out and suddenly you are fighting
       a Mancubus, then 2 Revenants with some Imps in the background.
    
       At some point, 2 more Mancubi and a Cyber-Mancubus spawn as well.
    
       Note that there's BFG ammo here, so if you are full, feel free to use it!
    
    Mission 10: Pounding Rock Area
    
       When the pounding rock is down, quickly climb onto it. It'll lift you up
       to a Skull Switch: press it, and drop down.
    
       Before continuing, to toward the Yellow Door, which is currently gated
       off. Look for a small alcove continuing the Classic Doom Map Lever. Pull
       it. The gate to the Yellow Skull Door will open: go that way and go back
       to the lower Toxic Sludge room (where the Mancubi appeared with the Elite
       Guard), and you'll find CLASSIC MAP 10.1 "Phobos Anomaly": SECRET 10.5.
    
       Go back to the Pounding Rock Area. Go toward a gated off green teleporter.
       Look left to see a large room with 2 Yellow Lifts and a Suit of Armor in
       the middle.
    
       Go in to what I call the Treasure Room, and pick up some loot and a Blue
       Skull, a fight is triggered on the way out.
    
    Mission 10: Fight: Treasure Room
    
       It starts right near the entrance/exit with 3 Spectres. This is quickly
       followed by some Imps and 4 Lost Souls. Then 2 Cacodaemons and 3 Mancubi.
       Finally, a Hell Baron.
    
       CHECKPOINT.
    
    Mission 10: Segue
    
       Now, after checking for stray supplies, enter the green teleporter (the
       bars will disappear as you approach).
    
       You'll be in a fiery yellow lit area.
    
       Grab CODEX ENTRY "Artifacts / Slayer's Testament V". Turn left for SECRET
       10.6: a Mega Health (don't forget Rich Get Richer upgrade).
    
       Continuing along, you'll be back at the Rectangular Pit.
    
    Mission 10: Fight: Rectangular Pit, Blue Skull Door Fight
    
       A Berserk Powerup has been placed for this fight. It starts with many Imps
       and also include a 3 Hell Knights, 2 Summoners, a Mancubus. It ends with a
       Hell Baron.
    
       Use the Blue Skull, and find immediately on the floor CODEX ENTRY "UAC
       Personnel / Olivia Pierce".
    
       Jump into the red teleporter.
    
                               Mission 11: The Necropolis
    
       You find yourself in a central area of this level with the Yellow and Blue
       Skull doors adjacent.
    
       Notes on Combat Challenges:
    
         * A Pin Pops a Balloon: there are two clear opportunities for this.
           Right at the beginning, and after crossing the floating islands with
           Cacodemons. Try both, since it can be pretty easy to kill the Mancubus
           accidentally. Dazed and Confused Rune can help a little as can ???.
         * Two Mouths to Feed: when you cross on the floating islands there's an
           easy place to get this. Use Gauss Cannon / Siege Mode or BFG.
         * Wait For It: By kicking the first barrel down the steps you can get 3
           there; and the pre-fight in the Square room has 6 Possessed that are
           easy to get. There's a number of other chances if you don't die on
           those scenes (the kills count even if you die!)
    
    Mission 11: Yellow Skull
    
       To your left at ground level is a teleporter. Jump into it.
    
       Find CODEX ENTRY, "Monsters / Cyber-Mancubus".
    
    Mission 11: Fight: Yellow Skull Prefight
    
       Continue along to a barrel at the top of the stairs, if you kick it down
       you can shoot it to kill some demons, for the Challenge.
    
       Descend the stairs and quickly look back to shoot 2 Lost Souls. A Mancubus
       appears at the top of the stairs: he's a good one to use for the Pin Pops
       a Balloon Challenge. If you climb the stairs, 2 more Lost Souls appear.
    
    Mission 11: Treats
    
       A CODEX ENTRY "Artifacts / Slayer's Testament #6", Gas, and ARGENT CELL
       11.1 (the last) are found by continuing down the corridor.
    
    Mission 11: Fight: Traps
    
       Go back up the stairs to where a gate has opened: you should see a Skull
       Switch straight ahead in the next room, but as you approach it, a bunch of
       Unwilling and a Spectre spawn.
    
       Kill them and actuate the switch, causing 2 Hell Knights to spawn as you
       return. Go back down the stairs and kill a Cyber-Mancubus.
    
       CHECKPOINT.
    
    Mission 11: Fight: Square Arena
    
       This is a square torchlit bloody room with 4 big pillars.
    
       Prefight: there a bunch of Unwilling roaming about and barrels: use them
       to work on the Wait for It Challenge. It's your best opportunity.
    
       After pressing the switch, the fight proper begins.
    
       3 Cacodaemons spawn, 2 Hell Razers and some Imps and 2 Spectres in quick
       succession. Then 2? Hell Knights and a Summoner.
    
       Grab the Auto-Map, pull the Classic Map Doom Lever, and grab the Yellow
       Skull.
    
       CLASSIC MAP 11.1 "Doom - House of Pain" is SECRET 11.3. Go back outside
       this room and down a hall to an area that looks funky on the map.
    
       This will trigger the teleporter to open, and you can take it to return to
       the central room you started in.
    
       On the opposite side, a new Teleporter has opened. This one will get you
       the Blue Skull.
    
       Go through the teleport for the next fight.
    
    Mission 11: Fight: Four Platform Arena
    
       Soon upon entering, 2 Mancubi form on 2 of the platforms (two Gauss Cannon
       Siege Mode blasts will take both of them). Then 3 Cacodaemons and Imps.
       Then some Revenants and a Hell Knight ends this wave.
    
       The gates surrounding the Quad Powerup lift and 4 Revenants spawn, one on
       each side of the square. Then 2 Cyber-Mancubi and 2 Mancubi spawn: the end
       of the fight.
    
       Take the Blue Skull. Teleport back to the Central Room.
    
    Mission 11: Fight: Central Room
    
       Use both Skulls, an interact with the knobs behind each door to trigger
       the next battle.
    
       3 Imps spawn in reliable location.
    
       2 Pinkies are next.
    
       2 Revenants, a Hell Knight and ? Spectre make up the next wave.
    
       The final wave is 2 Hell Barons.
    
       After the fight, two stair cases open up below the main area (see map), go
       there and drop into a small hallway with some health and another drop.
    
    Mission 11: Fight: Cacodaemons in Air
    
       When you stand up from the jump, there will be 3 Cacodaemons lurking
       around.
    
       Use BFG or (better) Gauss Cannon Siege Mode to get the "Two Mouths to
       Feed" Challenge.
    
       Jump onto the next platform, which has two large unlit torch/pillars on
       it.
    
       The next platform has just one torch/pillar. Peer carefully down from the
       edge to see a small island. Sometimes you can catch sight of it from
       above, but often you cannot, but there is a doll on it. In-Flight Mobility
       helps (but is not necessary) to jump down there. This is SECRET 11.2,
       COLLECTIBLE 11.1 "Chainsaw Model, Tealguy".
    
       Continue hopping to the cave, where you will be greated by a Mancubus.
    
       Don't forget to get ELITE GUARD 11.1, and there's some armor too.
    
       Continue along to some shotgun ammo and the last FIELD DRONE 11.1.
    
    Mission 11: Fight: Big Battle In-Progress
    
       Go up the stairs so where some big demons are duking it out: 2 Mancubi,
       some Revenants, Imps, and a Cacodaemon. Help them kill eachother and kill
       the Hell Razers, 2 Cyber-Mancubi and whatever else spawns. There's a BFG
       and a Haste Powerup.
    
       You'll want to get in good shape for the next fight.
    
    Mission 11: Fight: Paired Hallway
    
       The same demons will spawn on each end of this hall. I'll give total
       numbers:
    
         * 2 Hell Barons
         * 2 Mancubi
         * 4 Spectres
    
       There's quite a bit of ammo around, and ELITE GUARD 11.2.
    
    Mission 11: Fight: Last Non-Boss Fight
    
       Exiting, 2 Cacodaemons will immediately stalk you: kill them with the
       rocket launcher: there's ammo around.
    
       Walk down to the treasure trove with a big armor. This will trigger 2
       Mancubi to spawn. Retreat back to the original area and use Rockets, Gauss
       Cannon. Once you kill a Mancubi, 2 Hell Barons will spawn. Gauss Cannon or
       BFG is recommended: it won't take long for them to get to you.
    
       Now, you can get an obscure secret, SECRET 11.1. Look at the large statue
       / structure that is shaped like the head of a horned screaming demon. In
       its forehead, is a glowing pink rune symbol. Shoot it (with Gauss Cannon
       or Rocket Launcher, since you need range), and a weird cubic capsule will
       spit out of it and land next to you. This is COLLECTIBLE 11.2 "Gauss
       Cannon Model, Hazmatguy".
    
       Stock up, there are two Boss Fights coming up.
    
    Mission 11: Boss Fight 1: Hell Guard
    
       This fellow has a force field (the transparent green sphere) that'll
       protect him from everything, even BFGs, so you must time your shots for
       when the field is down. Most of his attacks give you an opening.
    
       His moves:
    
         * Club Attack. He comes at you, move and aim, since his field is down as
           he attacks, and right afterward.
         * Charged Club Attack. Similar, but he puts more into it and damages
           everything is a radius (which briefly flames up).
         * Tri-Sphere Attack. He blows up a glowing yellow sphere, which briefly
           flashes, then turns almost white, then 3 very damaging shots are
           launched out. This can only be attacked after blinking but before
           shooting. The good news is that it stuns him for a bigger (Siege or
           BFG) secondary attack.
    
       Midway through the fight he gains some new tricks:
    
         * Spinning Flaming Spiral. Avoid the flames: after this he'll be
           attackable for an unusually long window.
         * Three Drum Waves. He beats the ground creating a relatively slow
           moving wave that does a lot of damage.
    
       Toward the end, you may wish to equip Dazed and Confused, since he doesn't
       stay staggered long, and you have to Glory Kill him.
    
    Mission 11: Boss Fight 2: The Twin Hell Guards
    
       These guys really act in concert, but it's easier to describe their moves
       separately. They lack the force-field, fortunately.
    
         * Bed of Fire. One runs creating a sequence of long fireballs. Just jump
           over them.
         * Fire Tornado. One spins creating a whirlwind of fire. Avoid.
         * Sphere Attack. Like above but it doesn't flash or trifurcate. Shoot it
           right after it finishes inflating to stun him.
    
       When one is stunned, you can often line them up to get double damage out
       of Siege Mode or BFG.
    
       When they are getting low (20%), switch on Dazed and Confused so that you
       will have an easier time Glory Killing them.
    
       After killing them, access the Crucible (which looks more like a dagger
       with a Skull at the top).
    
                          Mission 12: VEGA Central Processing
    
       Notes on Combat Challenges:
    
         * Variety is the Spice of Death III: there's a lot of Imps, including 4
           right soon after entering the building.
         * Gore Pinata: Plenty of opportunities for this as well.
         * My Teeth are Sharper: you can jump and chainsaw if needed.
    
    Mission 12: Intro
    
       Enter either door, and in the Console area look for CODEX ENTRY "UAC
       Personnel / VEGA".
    
       Proceed to open the airlock, and get Gas or Ammo if you want it. Stop
       about 115 meters shy of the waypoint. Look for a green-lit Mainenance
       Hatch. Enter it instead of going to the waypoint.
    
       In one shaft here find COLLECTIBLE 12.1 "Hell Guard Model / Quakeguy"
       (SECRET 12.1) and a BFG ammo in the next shaft. Drop into the main area
       from the first shaft, possibly conservatively since there's about 5 Imps
       in there.
    
       Another Maintenance Door at ground level is followed by a green-lit hatch
       in the floor.
    
       Drop down to the area with the Security Switches.
    
    Mission 12: First Switch Fight
    
    Mission 12: Security Shutdown Fight
    
    Mission 12: Cooling Access Fight
    
       Note: you can use the Berserk from the earlier fight.
    
       A few Possessed Securities and 3 Pinkies and a Mancubus scattered across
       about 4 rooms. A Health Station and CODEX ENTRY "Monsters / Revenant" are
       found near eachother. There also two Elevator Shafts off to the side that
       have 2 Possessed Soldiers and a BFG ammo.
    
    Mission 12: Finding the Blue Keycard
    
       Back near the Health Station look for a very bloody side area with
       entrails hanging from the ceiling and a chainsaw. Enter and look for a
       hatch.
    
       Drop down to find a bunch of Possessed Engineers, The Possesseds, and 2
       Spectres.
    
       But most importantly, the Blue Keycard.
    
       Go through the Blue Door.
    
       Turn Left to find the Auto Map (if you haven't already), and continue in
       through another Blue Door.
    
       You'll find a SECRET 12.2, ELITE GUARD 12.2 here, and get surprised by a
       Revenant.
    
       Behind the crate that the Guard is leaning on is a Lever: pull it to open
       access to the classic doom level. Then go back past the Blue Keycard guy
       and look for a nested pair of crude circles on the map. That is SECRET
       12.5, CLASSIC MAP 12.1 "Doom - Commend Control".
    
       Look down the shaft the Revenant popped out of. You'll see a Mega Health,
       drop down, making sure to get it.
    
       You should be standing on a rectangular duct in a very large icy tunnel.
    
       Drop down the other way for SECRET 12.3, COLLECTIBLE 12.2: "Cyber-Mancubus
       Model, Jungleguy". Walk along the duct to get back up. Enter the door to a
       tunnel.
    
       It'll drop you into a lobby where a holographic guy is blathering about
       how much energy they use.
    
       Continue on.
    
    Mission 12: Fight: Coolant Generator Room
    
       Four Switches must be destroy (by shooting) to reroute the energy. It
       doesn't seem to matter much what order you go in.
    
         * Switch 1: 2 Cacodaemons and a Summoner spawn, and a long parade of
           Possessed Soldiers and Hell Razers and a few Imps.
         * Switch 2: A Hell Baron, 2 Pinkies, another Summoner, 4 Lost Souls.
         * Switch 3: Imps, Possessed Soldiers, Hell Razers
         * Switch 4: Nothing new spawns :)
    
       After the Demonic Presence is eliminated, and you have taken all the
       remaining loot, go to the waypoint and actuate the screen.
    
       Cheesy Strategy: You can hide behind lowest switch: eventually Pinkies
       will gang up on you, but then you can take advantage of the Berserk
       Powerup in the tunnel leading out of the area. So, the way I usually do
       the fight is go left past one switch, then go right and jump up across the
       gap to the second switch. Use Tactical Scope to take out the first 2
       switches from the same vantage. Then go outside and jump down to the 3rd
       switch; sometimes a Cyber-Mancubus will spawn there before you jump:
       either chainsaw him or go over/around. Destroy the 3rd switch and hide
       behind it, shooting out with the Gauss Cannon / Siege Mode etc. At some
       point, grab the Berserk. The cool thing about this is that the monsters
       mostly fight each other.
    
       There's also CODEX ENTRY "Monsters / Cyber-Mancubus" in this room.
    
       Follow VEGA's suggestion to jump down onto a train below to enter the last
       big battle on Mars.
    
    Mission 12: Fight: Finale
    
       This takes place in a large depot area, with a few BFG Ammo, Gas cans, and
       other supplies littered about.
    
       You'll ride the train in and a well-timed BFG can take 2 Cacodaemons and
       the 2 Hell Barons plus a whole lot of random demons. Fire it at the 2 Hell
       Barons, just as the Cacodaemon at left is about to go out of view.
    
       The next wave consists of a few Cyber-Mancubi, 5? Pinkies, and 3?
       Cacodaemons, along with many Imps.
    
       There are 3 BFG ammo here - so you'll probably want to use it a few times.
    
    Mission 12: Destroy VEGA
    
       A waypoint leads to a platform that'll carry you up to ???.
    
       But first, look down below for another platform to jump onto. Jump onto a
       ledge which should have SECRET 12.4, ELITE GUARD 12.3 on it.
    
       Take the elevator back up to the platform.
    
       Wait on it, until you get to a dramatic platform area.
    
       Disable the Neural Networks on the left and right.
    
       Then go to the center console. Pick up CODEX ENTRY "Environments / VEGA
       Central Processing". Then interact with the screen to get a cut scene that
       ends the level.
    
                                Mission 13: Argent D'Nur
    
       Notes on Combat Challenges:
    
         * Hold Still: only the third fight is good for this, so be careful that
           you have both Barons in sight when you use the BFG. It would be
           difficult to use the Gauss Cannon to achieve this.
         * Uncharted Territory: follow the guide.
         * Big [REDACTED] Gun: you'll probably get this without trying; you
           probably want to enable Ammo Boost II a lot to get even more BFG ammo.
    
    Mission 13: Introduction
    
       You start in a large upper courtyard area with loot scattered about.
    
       Eventually, go down to a CHECKPOINT for the fight.
    
    Mission 13: Fight: Sniper then Berserk
    
       You should start at an overlook, where you can see a Cacodaemon attacking
       a half dozen Imps. I usually kill the Cacodaemon (Assault Rifle with
       Tactical Scope) from afar and save the Imps for up close.
    
       Jump down to the courtyard area below and polish off the Imps who will
       come to you. The next wave won't start until you enter the main area.
    
       In short order, 2 Hell Knights and a Summoner appear, followed by 2
       Pinkies and many Imps.
    
       I usually use one BFG after lots of demons have spawned, then grab the
       Berserk Powerup from the very center of the courtyard.
    
       In theory it seems like the "Seek and Destroy" and "Savagery" Runes would
       may the beserk powerup more effective - I didn't really notice a
       difference though.
    
       When done, exit via the waypoint and CHECKPOINT near the blue teleporter.
    
    Mission 13: Fight: Intro Stairs
    
       Before starting, look ahead to an impressively demonic sight of 3 statues
       feeding some central thing. (I'm not sure if the 3 beams symbolize the 3
       major fights ahead or not)
    
       Descend to the next level where there is usually between 1 and 3 Unwilling
       staggering around (they will fall down to the next level but they can't
       get back up, so the exact number varies).
    
       (Because I often seem to need the Mobile Turret upgrade, which involves
       killing in groups of 4, i often wait to kill them, but the Secret has to
       be triggered before you drop down to the next area)
    
       Facing out toward the canyon, look for a Skull Switch at the right-side of
       the level. Actuate it, then go to the other side of this area and look for
       some blocks to climb up. After climbing up, there is a cave just a bit
       ahead that opened up with Gas and BFG Ammo: SECRET 13.3.
    
       Go back down to the lowest area in this complex with about 8 Unwilling.
    
       Optional: go through the tunnel to the left. Once you take any armor at
       the end of the tunnel a Cacodaemon will materialize directly in front of
       you, and 2 Imps will appear in the hallway. A few seconds later a Hell
       Knight will appear at the far end of the hall (the entrance). (I usually
       use Gauss Cannon Siege Mode for the Cacodaemon and the Hell Knight -
       separately - and super shotgun for the Imps, but there's many options.
       Using a chainsaw on the Hell Knight could make things easy and give you a
       lot of ammo)
    
       Optional: go the other way (a right turn, if facing the canyon), to a
       rocky set of stairs leading up to the Auto-Map for this level.
    
    Mission 13: Fight: Stragglers on the Islands
    
       Jump across the gorge: keep an eye out over the canyon where 2 Lost Souls
       and then a Cacodaemon will spawn.
    
       Jump down and across the canyon.
    
       Go left and turn around to see the next jump.
    
       2 Cacodaemons will appear, one at at time, after you jump across.
    
       This island has two levels: climb to the upper level to see the next jump
       target, relatively far below with ??? ammo.
    
       Continue along to an area with a left and right branch: the waypoint leads
       left, so instead go right to be surprised by 2 Imps. There's armor here
       (etc??)
    
       Go back to the left route, and (I recommend) activate In-Flight Mobility.
       Jump around the giant stalactite.
    
       Drop down to hear a demonic voice say "Kill Him".
    
       CHECKPOINT.
    
    Mission 13: Fight: Big Fight 1
    
       You can start by sniping the Imps and Hell Knight, if you can see them
       from the cliff (you usually can). This can be a good time to get the Gauss
       Cannon's Precision Shot upgrade.
    
       Once you go down (irreversibly) into the arena, this fight is dominated by
       6 Pinkies and 2+ Hell Knights and a Cacodaemon.
    
       There's a Mega Health right after the CHECKPOINT for this, so it's quite a
       good place to start with Rich and Richer with Gauss Cannon / Siege Mode.
    
       There's a Quad-Damage Powerup here as well.
    
       Post Fight: there's a bunch of gear and a near the first Wraith's Soul.
       (This pattern will continue for the next two fights)
    
       There's are two parallel stairways leading up there: the one on the left
       has a Skull Switch that you should press.
    
       Go to the waypoint by first jumping to the high platform on the far side
       of the entrance (it has a BFG ammo on it, initially). From there, jump
       into the pale green mouth of a demon statue: it's lit with candles.
    
       Immediately past the mouth, turn right to a passage that only opens after
       the Skull Switch is pressed: this is SECRET 13.2. You'll find Gas and BFG
       Ammo.
    
       Continue down this secret passage, looking for bloodsmears and a lever on
       the left wall. As usual, interact with the level to open SECRET 13.5,
       CLASSIC MAP 13.1 "Doom - Pandemonium".
    
    Mission 13: Fight: Big Fight 2
    
       Again, snipe a Hell Knight and 2 Imps from above, if you like.
    
       This fight starts with a Pinkie but I think there's only 1. There's tons
       of Hell Knights, Revenants, Imps, Hell Razers. And a string of about 4
       Cyber-Mancubi that tend to come at the end. The finale is a Cyber-Mancubi
       and Hell Baron that spawn at the same time.
    
       There's a Berserk Powerup here. Don't forget to use the chainsaw if you're
       low on ammo.
    
       Post Fight: on the way up to the waypoint (a Wraith's Soul), there's a
       bunch of supplies. On the left stairs going up, look for a big in the
       upper half of the stairs that's so big you can walk in under the stairs.
       This is SECRET 13.1, COLLECTIBLE 13.1: "Chaingun Model, Cosmoguy".
    
       Continue up to interact with the waypoint, then follow the waypoint to the
       next fight.
    
       You'll teleport to an area with molten rock. At you walk up this tunnel,
       keep an eye out for the third Skull Switch, on the right. Interact, then
       walk back toward the entrance to find an newly opened alcove, SECRET 13.4,
       containing Meta Health and BFG Ammo (don't forget to activate Rich get
       Richer before taking the health).
    
    Mission 13: Fight: Big Fight 3
    
       Again, snipe a Hell Knight and an Imp before jumping down, if possible.
    
       This fight is a long sequence of Hell Knights and Pinkies and Imps. Toward
       the end a Cyber-Mancubi and finally 2 Hell Barons- you're easiest chance
       to get the Hold Still Challenge (use the BFG of course).
    
       Post Fight: gather supplies and interact. Follow the waypoint to the last
       fight, a boss fight.
    
    Mission 13: Boss Fight: Spider Mastermind
    
       This is your big battle with demonic Olivia Pierce.
    
       Unlike the other boss fights, this one doesn't have a checkpoint in the
       middle.
    
       The first phase of the fight, is pretty standard:
    
         * Rocket Volley: a fast sequence of rockets. Keep moving in one
           direction to dodge.
         * Back-And-Forth Laser: a red laser that swipe one direction low (so you
           must jump over it) then it swipes back high, so you must crouch under
           it.
    
       When the demon gets to 50% health, she'll add:
    
         * Toxic Pond: Pillars sprout up that you must stand on, as the ground
           will be very damaging to stand up. The first time, that's all that
           happens. Subsequent times, Olivia will concentrate on the pillars, and
           when she jumps spikes will come out of the pillars, killing you if you
           are standing on them. Double jump in the air to avoid this fate.
    
       When she gets to around 10% health, she kind-of goes nuts, shooting many
       (fairly weak) lasers in all directions, and emitting these weird cubic
       missiles that do a lot of damage (dodge them).
    
       When she gets to 0% she'll stand up like she's going to attack or
       something, but she actually flops down and is Glory Killable. (There's no
       time limit, she won't recover from being staggered)
    
       You'll get COLLECTIBLE 13.2 "Spider Mastermind Model, Goldguy".
    
       After that, watch a cut-scene and the credits.
    
                Appendix: Ultra-Nightmare Practice Sheet: Abbreviations
    
       You can download a practice sheet if you want to try to train for
       Ultra-Nightmare, and any player could use it to improve their skills.
       (TODO: as of 10-31-2017 I haven't yet actually made the practice sheet)
    
       Abbreviations for the Demon that killed you:
    
         * tp: The Possessed
         * uw: The Unwilling
         * ps: Possessed Soldier
         * ss: Possessed Security (aka Shielded Soldier)
         * hk: Hell Knight
         * imp: Imp
         * ls: Lost Soul
         * cd: Cacodaemon
         * mc: Mancubus (plural: Mancubi)
         * cm: Cyber-Mancubus
         * hb: Hell Baron
         * pnk: Pinky
         * sp: Spectre
    
       Modifiers:
    
         * immed: Immediate (w/i a few seconds) death from Checkpoint
         * oob: Out-of-the-Blue
         * ow: Overwhelmed
    

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