• Modern Warfare 2. best multiplayer game i've played in a LONG time. i'm actually neglecting my guitars :-\ haha
• Borderlands. tons of fun with or without friends. if you have friends with the game be prepared to play for HOURS. great game
• Mass Effect. old one but a good one. you can find it for cheap, and it's a classic
• Assassin's Creed (1 or 2) nothing quite like being the silent assassin. 2 only made it better, too.
• Grand Theft Auto 4. with the expansions and all the gameplay it's hard to pass it up. it's not my first (or even second) favorite GTA title (Vice City and San Andreas came before) but it's definitely one well put together game. and after you're done playing the main story you can download the expansions and play them.
besides that, Fallout is a must have (already on your list) and 50 Cent is a surprisingly fun game, if you can laugh at all of it. ESPECIALLY if you have somebody else to play through the game with you. in co-op that game shines. single player is kind of annoying. just like Army of Two, which i would also suggest, but only really if you have somebody else to play with. great games, though.
