1. Fallout 3
I put over 100 hours into this game and loved almost every moment.
Just pure fun. I still want to play this constantly, just need some coop players. most of my buddies have moved on from this one, but i can not get enough.
3. Call of Duty 4: Modern Warfare
I put way to much time into the multiplayer, and think it has ruined me for this style multiplayer.
4. Left 4 Dead
Amazing what else can I say?
5. Burnout Paradise
Fantastic game. The example for developer to community relationship.