Halo 2+3 and Call of Duty 4: Lunge attack melee system: This throws me off every time I try to play a game without this melee system.
Narrow Field of View on widescreen monitors: This puts you at a bigger disadvantage when playing against people who have standard 4:3 monitors, typically you lose your peripheral vision on the top and bottom, instead of gaining more on the sides.
Random Battles: No further explanation.
Space Marines: Stupid plotline.
Realism: Why do we have to have more "realistic" games instead of fun games?
Sniper Rifles: The only weapon that should be made "realistic" since I am getting sick of seeing everyone whore the sniper rifle.
Bullet Hell games where the enemy is too fast and too strong (health wise:) This only makes dodging bullets harder than it should be, since killing enemies helps reduce the number of bullets appearing. I'm looking at you, Subterranean Animism.
Excessively long combos: Self explanatory. Gets even worse when there is an infinite combo glitch with said combo.
Overpowered boss: Dead or Alive 4. End of comment.
Un-skip able cutscene: "We are going to make great graphics, so why not make the cutscenes un-skip able to make gamers admire it?"
Un-skip able [insert developer/publisher] intro: I hate this so much. When you start a new game, it's fine seeing: [game developer] presents:, but when I have to see this before I get to the menu in un-skip able form, I get pissed. One forced viewing is fine. I don't need constant reminders that I am playing their product. I know already.
Lack of auto-balance team options in multiplayer: Don't you just hate it when all of your team mates quit on you?
Matchmaking: I am not stupid, I know how to host/join a fucking match. Let me do this on my own, thank you very much.
Regenerating health: Stupid, takes away from the challenge of the game. They should combine this with a health bar instead, only allow you to regain a little bit of health from damage.
Overdone HDR bloom effects: I CAN'T SEE ANYTHING.
Bullet physics calculations that make no sense: So I can't shoot through a cinder (sp?) block, but I can shoot through both 1-inch thick steel container walls?