the majority of sports games. If i want to play a sport, i'll...go and play a sport.
Driving games. I used to play a fair few but now they just bore me to tears. Going round in circles is not my idea of fun.
Single player (i stress the single player part) open world games. I can't stand the ones that give you to much freedom. I find myself wondering what to do next, as once you've explored a bit, gone on a rampage, pillaged a few towns, it all becomes a bit samey

. GTA and Oblivion are the main culprits i've played. I think the concept only works well when you have other players involved, who influence the world.
Also while i'm a big RPG fan, i despise ones in the genre that insist on grinding, which is probably why i can't stand WoW tbh. Spending hours killing the same thing over and over again, in the same spot bores me. RPG's are about exploration, not standing in one spot slapping a monster in its face with your sword.
Party/Music games, you know the sort. I dunno, i just don't see the appeal in stuff like Guitar Hero or Rock Band, I'd rather learn a proper instrument. Always reminded of the South Park episode that parodies guitar hero when i think of it.