I'm assuming that is 360 only:
1) DEAD RISING - Save system be damned, I had more fun with this game than any other game in past four years. I know it's got a lot of flaws, but it's got a hell of a lot more redeeming qualities (especially for a Zombie nut like myself).
2) Gears of War - Best 360 game, PERIOD. I know alot of people want to talk about how it's over hyped, how it's the same thing over and over again. Those people just have to learn to play a game more than 30 minutes before passing judgement on it.