Got my list right here:
1. Female characters which consist of enlarged mammary glands with legs. Note to game industry: LOSE THE %#?! 14TH CENTURY GENDER ROLES.
2. Male characters which consist of an enlarged phallus/sword/gun with legs. (See note above.)
3. The chatty/witty/saucy sidekick, who ends up displaying all the horrible gender/racial/sexual/national stereotypes not covered by points 1 and 2.
4. Cinema-to-game videogames. Ah, the horror, the horror...
5. The triple-dip final boss with a ridiculously overpowered third form who has the time to deliver a 15-minute preliminary monologue about his/her massive Evilocity, although for some reason your player-character never has the time to heal or gear up.
6. Genre clash. This is when a perfectly fine action game decides to play a dice-rolling minigame, for no apparent reason than the designers ran out of ideas and decided to torment players instead of doing their jobs.