Haven't played a lot yet since a lot of good games were coming out on other systems, but so far it's looking like this:
Retail games I'm playing/have played
Call of Duty 2
Perfect Dark Zero
Retail games I will be playing when I finish other games
Far Cry: Instincts Predator
Ghost Recon: Advanced Warfighter
Elder Scrolls IV: Oblivion
Arcade games I've played/owned
Geometry Wars Evolved
Street Fighter II Hyper Fighter
Marble Blast Ultra
Outpost Kaloki X
The arcade games are great, they fill up a lot of time. COD2 is a great WWII shooter, even if it's multiplatform. It just plays very, very smoothly on the 360 and I just love the accuracy of the guns in the series. Amped 3 is a cool game, it's snowboarding and it's fun but the best part about it is the cutscenes and the humor. VERY artistic and creative (and hilariously weird).
PDZ is a cool game, the kind of FPS I like to play with controls that I love (not a fan of Halo's control/aim system). The levels have been neat so far. I've wanted to play an FPS with REAL missions for a long time now (as opposed to having a "mission/goal" with a lot of neat description when it's really just "kill stuff while moving from point a to point b"). The AI can be annoying at times, especially Jack Dark... I found it hilarious how at the end of the first mission, he literally ran around like a dumbass in the middle of a fire fight taking like 100 bullets. But it really sucks in another mission where you're separated from him and have to protect him from the rooftops. No matter how well you protect him, he's likely to stand out in the open like a craphead getting himself killed while you move from waypoint to waypoint. Anyway, I'm having fun with the game so far, even if nearly all of the achievements require multiplayer/co-op.