SS2 Multiplayer Breakdown, by jesdynf (of EFNet).

Astonishingly, I couldn't find any details on SS2 multiplayer gameplay 
on the net. So permit me. This document contains technical data, 
specific gameplay notes, and analyses of the game flow. It was 
deliberately left unedited of conflicting opinions; you might as well 
see the thought that went into both positions.

...

SS2 multiplayer uses DirectPlay. If you're behind a firewall, you need 
to have the following ports open or forwarded: 6073 UDP, 2300-2400 
TCP/UDP.

Two to four players may play.

The difficulty is pegged on hard. Cybermodules are shared among all 
players, each player recieving a 100% share. Logs, email, status 
messages, and all vocal events are percieved by all players. All players 
share research. Map information is NOT shared; you'll see player 
locations, but you won't have the map sector filled in.

All players show up on the map and minimap, but they don't appear to 
register to psionic abilities. Players are protected from friendly melee 
blows but NOT from ranged or psionic attacks. Players have the same 
overly generous bounding box all game entities share.

Despite the difficulty being on hard, dying costs zero nanites. Should 
you be slain in a region without an active ressurector, you will respawn 
at the entrance to the level -- with no loss of EQ or nanites. In other 
words, you cannot be made to stay dead.

Alt-clicking nanites and multiple inventory items lets you split items 
out of a pile to better share resources. Press ['] to chat; press [Esc] 
to break out of an unsent message.

If anyone leaves a level, everybody does, on the spot. It autosaves 
after it successfully loads the level.

We found the game to be more stable than we had any right to expect. One 
crash in seven or eight hours of playing time... and not one single 
second of lag, though we all had broadband. The netplay is rumored to be 
awful for modems.

...

These changes in gameplay have several implications.

(#1) Ammo and weapons are unchanged, so if three people will share them, 
that's pretty freaking scarce.

Weapons, ammo, and nanite counts haven't been changed one bit. If you're 
sharing the weapon stash with two other people, like I was, they may not 
stretch all that far. Especially for the first couple of levels. If you 
have multiple people who seriously wish to play Marines, consider having 
someone learn high-level Repair. You'll need to make the most out of 
every weapon you find. Research is also crucial if you want to be able 
to use Exotic-branch weaponry.

(#2) Someone else knowing a skill is almost as good as you knowing it.

Only ONE person needs any of the technical skills, so specializing 
leaves you many more points for things you find interesting. Don't spend 
even a single point on the tech skill you aren't going to max.

(#3) It doesn't matter what you do, you're gonna be okay.

I'm -not- pleased with the MP ressurection policy. Charging a well-
fortified position, like the security station near the entrance on deck 
3, is okay, and if you die nine or ten times between you, no worries. 
Still, there's nothing to be done for it.

(#4) You can't buy only four OS upgrades; you can buy a huge boatload of 
them.

Every person gets four. Be creative. Someone should DEFINITELY buy 
Replicator Expert; and it doesn't have to be the Navy guy. Spatially 
Aware is useless, of course, but knowing others are gonna take the load 
off you enables some possibly unusual buying decisions.

(#5) Don't shoot over someone's shoulder. Shoot AROUND their shoulder.

Remember that one egg on the Rickenbacker? Behind the turret? The turret 
that you HAVE to shoot to death 'cause you can't hit the egg you can see 
with your own two eyes? Uh-huh. Now take a shot at a rumbler, and zing 
that grenade just over your ally's shoulder... oops. Strafe and THEN 
fire.

...

I believe three people is the optimal number of players -- one from each 
branch, and specializing accordingly. Two would work, and four would 
stretch available resources pretty thinly, but three gives you just the 
right balance of interaction and shiny toys.

Note that of all the tech skills, two of them -- Research and 
Maintenance -- don't rely on the CYB stat. This suggests a very 
attractive divison of labor:

The Marine, who goes with combat skills and a max Research. You need to 
be able to use everything that comes to hand, and the damage bonus on 
Midwives that Research grants isn't anything to sneeze at. Remember that 
you only need Research-5 with the LabAssistant. For weapons, I'd go with 
Standard-6 and Heavy-6. You might buy T2 psionics as well; you get some 
nice defensive abilities.

The OSA geek, who goes with awesome psionic powers and Maintenance. It 
doesn't need CYB to work, AND you get the +10% charging bonus per level 
of Maint when you charge things with Electron Cascade. Refurbishing a 
Marine's Powered Armor and the Navy swab's EMP Rifle at 150% max is a 
good feeling. The OSA guy should max out Exotic, and take Energy-2 or 3. 
A laser pistol's great 'cause it doesn't need any ammo your psi skill 
can't provide.

Finally, there's the Navy player, who gets high scores in the three 
remaining skills (and give serious thought to skipping over Repair 
entirely), and should learn Heavy-3 or 4 for grenades, Std-3 or 4 for 
the shotgun (save ALL pistol ammo for the Marine), and Energy 2 or 3 for 
the Laser Pistol. Might get Exotic as well, but that's stretching it, 
since the sailor's in a prime position to get some low to middling 
psionic powers. Some of the stuff on T3 is very, very nice, and T1 
offers the absolutely indispensable Cyberaffinity. Do NOT mock that +2 
CYB; like I said, you're gonna be short nanites a lot, and our tech this 
game has had no less than three critical failures so far, trying to 
stretch his nanites. Not to mention all the modding he has to do.

Three people; Marine as gun bunny, OSA guy as stealthy recon, and Navy 
as tech and backup for the Marine. Of course, that's all roleplaying; 
what REALLY happens is that everyone splits off and goes exploring, and 
if you die two or three times taking a particularly troubling section, 
what harm? Still, it's a lot of fun, chatting to request the hacker take 
out the cams, or asking the Marine for backup, or getting called over to 
take a quick psychic looksey at what's coming.

...

Alright, we just finished playing.

Three people, about eleven or so game hours to ice Shodan.

My advice? Quit playing when you finish cleaning out Deck 6. It's just 
gonna get very tedious, very fast.

Deck 7, the Rickenbacker, is just one long, long, long crawl. You get 
WormSkin (useless), the Annelid Launcher (probably useless), and a 
couple implants of strictly limited worth. Yeah, you find a pristine 
fusion cannon pretty early, and you've probably got a huge pile of 
prisms for it, but the fusion cannon never managed to impress me.

Deck 8, the Body of the Many, highlights the problem with the 
multiplayer ruleset. You see, when you play on Deck 8, there's no 
regenerator. So you save a lot. And if you hit a tricky section, well, 
you restart. At the beginning. You all do. So you do A LOT of walking. 
And if you die after a jumping puzzle? Do it again. And again. And 
again. If I hadn't had teleportation and been able to jump beyond it on 
death, we'd NEVER have won. We were about to give up when I finally 
killed the Heart with a laser pistol. It's not at ALL cool.

And Deck 9's just a joke. Nothing scary, three ninjas, ooo. SHODAN's a 
total freak; I was invisible and ICE'd her three security stations, and 
then I didn't have time to get around a pillar and assess the situation 
before someone gunned her down.

Very anticlimatic, in other words. 

WormSkin is useless because it eats psi points, and after I took down 
the Many I had exactly three psi points, and no psi hypos. The Annelid 
Launcher is only useful if someone takes Exotic-6; the Marine sure as 
heck isn't gonna, the Navy guy may if he saves his modules, but the OSA 
guy has no chance at all if he's interested in Tier5 psionics. Of 
course, this DOES mean that he doesn't need to spend anything on Exotic 
at all, if he's willing to stick with a wrench until he learns the psi-
amp melee attack.

It's a lot of fun up to when you leave the Rickenbacker. In practice, 
nobody's ever gonna have to get a recharge, and if you keep degrade down 
-- we played with it at 10% -- nobody's gonna need to have Maint done 
the whole game through, so you might as well ignore it.

What I said about Repair goes double. Forget the broken weapons, and we 
had AutoRepair kits to spare even at game's end.

So maybe Research isn't as stunning a priority as I hoped. After three 
(four with LabAsst) for the Crystal Shard, maybe you might as well pack 
it in and buy more Strength. \: Four points has to be enough to research 
all the monster organs.

If we'd been playing with four people we might not have had the 
resources to beat the game. We were badly stretched fighting the Many. I 
guess I could've turned all the med hypos into nanites... 

The OSA guy's entire paradigm is seriously compromised in multi. For 
every level before deck 7, there's absolutely nothing wrong with rushing 
in, killing two things, and dying. You'll clear a level no matter what, 
so shooting is more important than stealth and tactics. And at deck 8, 
players are gonna rush in, kill two things, die, then start hiking. Or 
die at the jumping puzzle. That's a popular option.

All in all... try it out, but don't be afraid to kill it when it gets 
boring. It will. Two people might work out better than three, but games 
like this aren't especially fun with just two people. Needs at least 
three to be hopping.

...

In other words, System Shock 2 is a very good single-player game. 
Multiplayer was plainly tacked on as an afterthought, and the careful 
level creation and play balance is completely lacking. Technically, it's 
a nice achievement... but it isn't something I'll ever have to play again.