enrageorange on 13 April 2011
I'm assuming this is consoles only so I vould say halo 3. Bioshock in second. Halo Reach in third.
Otherwise if pc is included as well. first Team Fortress 2, second Left 4 Dead 2, third halo 3.
The 360 versions of left 4 dead 2 and team fortress 2 lag behind their pc counterparts which is why they are higher if pc is included.
