Timers on strategy games, in StarCraft and alike, I like to build up slowly and unleash the biggest conquest ever seen to mankind. Timers kill my inner child.
And as someone has brought up here before, grenades. CoD4, most of the singleplayer campaign on veteran consisted of running away every time a grenade icon appearead on my screen, and they're ridiculously powerful. In opposition to the grenades in BF2, they shake your screen a little. And smoke grenades, in CS they make a thin layer of smoke which disappears after a few seconds. In CoD4, they cover a bout one square kilometre of thick fog, making it impossible for both you, and your enemy to see your own weapon.
And I could survive without grenade designs that wary from game to game "Wait... is this a flashbang, an explosive one, teargas, smoke or sunshine?"
I could also survive without moving sniper sights (yes, I'm looking at you CoD4 and Crysis).
In CoD4, you can hold your breath, but my character can't hold it for more then 5 seconds before making the aiming wiggly again. Yes, I know it's realistic, but after TF2 came out, I've been praising every game for it's lack of seriousity, games are supposed to be fun. I don't want to relive the Vietnam war as it was because some psychopath thinks that the world should learn how horrible it was.