I love Mafia 2 to death....hmm...... let's see....
Possibly never getting a 3rd in the series. Not really having free time in-between the missions to explore the city. Not enough to do in the city Complete missed opportunity to have mini games in it And for the time that it came out it could have done a lot more in terms of graphics.
Fallout 1/2. Existing combat systems and mechanics are interesting, but combat is ultimately very shallow. Still fun, but no depth, none what so ever.
Team Fortress 2. Some of the classes have lost almost all of their original identity (Demoman, Engineer, Sniper, Spy, I'm looking at you) and the game has become almost exclusively focused on offensive game play, with even the defensive classes rarely playing defense.
Mass Effect 2. Streamlined RPG elements. Mostly with loot.
I really enjoyed the way weapons, armor, and weapon/armor mods worked in ME1, I was disappointed to find it was all removed.
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There's something endearing about the animations of Morrowind. They just look so silly in the most fun way. The real problem with the game is the insane number of bugs. The shallow combat system. The imbalanced everything. The weak AI.
Warcraft 3. The community was killed by DotA, and the server list and out of game chat system left some things to be desired. Also those damn 30+ character save codes for various RPG maps.
Star Wars Jedi Knight: Dark Forces 2. After playing the sequels, you kind of realize the saberplay is balls terrible.
Doom 2. All of its problems are solved by source ports, so I guess this is the perfect 2.5D shooter. I can't think of anything wrong with this game from a gameplay standpoint.
Halo 3/Reach. The developers have so much trouble figuring out balance. Non-hitscan BR with spread was terrible. DMR with bloom was terrible. Frag grenades randomly fused to surfaces in Reach, too.
Diablo 2. So many skills that were just meaningless. And the game somehow always gets boring before I can beat Baal. I think I've beaten him a handful of times at most. So close every time, but I never find the energy to keep going.
Perfection. Where everyone fails. If you expect nothing you can be happy for everything.
Farming Simulator 2013: It's kind of an isolated experience. You're a farmer and you sell your produce on the market, but there's no other farmers and the only person doing anything to change the market prices is you.
Terraria: it gets boring single player. Minecraft: ditto, but yet, not as bad as Terraria
Deus Ex for me too. I've just finished it for the first time ever and it was amazing. It's one of 3 games that should be remade IMO. I disliked the fact that you could not sell anything and the lack of shops/vendors despite, at one point, being in an underground mall. Also, the graphics obviously suck and there is no option to join mj12.
By extension, deus ex invisible war is an obvious bastardisation of a PC game for consoles. The graphics are the sole improvement. The ammo system is awful, the hud is terrible, the levels are miniscule in comparison to its predecessor and, my god, the amount of loading screens is simply atrocious.
Following that my favorite game is the latest in the series, Human Revolution. I love everything about this game bar two things: boss fights are God damned ridiculous and the endings make no sense within the deus ex universe already established. Oh, and the directors cut for robbing me of the option of that lovely golden hue. Sods...