"Defeats are softened and victories sweetened because we did them together."

Doom, Marathon, Heretic, Quake, Hexen, Unreal, System Shock 2, Left 4 Dead, Gears of War, Open Co-op, Synergy, HL: Decay, Sven Co-op, Black Mesa, Co-op or Die, Co-op Warfare, Serious Sam, Ghost Recon, ArmA, Rainbow Six, SWAT 4, Rage, Aliens: Colonial Marines, The Scourge Project, Descent, Diablo, Neverwinter Nights...