Left 4 Dead [XBOX360]: While I only turn on my XBOX360 once every 3-4 months and usually just stick to my PC, last night a few friends harassed me into buying "Left 4 Dead" and playing online with them. It's hands down the best multi-player and "teamwork" experience in any game yet, and I normally hate online games since they're infested with teenagers - it's anything but. You're basically playing cooperatively in a "survival horror" fashion like 28 Weeks Later, playing against an A.I. based "Director" sort of like a dungeon master that keeps throwing new challenges (hordes of zombies) or help at you depending on how well or poorly the team is doing - its a constant struggle of never having quite enough resources, ammo, etc and having to struggle with the odds. Definitely great fun even for casual gamers that hate typical online gaming.

Grand Theft Auto 4 [XBOX360]: This game was like crack for a lot of people about half a year ago when it came out, but still a lot of fun even in casual play.