40. Unreal Tournament (PC, also on DC and PS2)
This game was a revolution and one of the first game marketed as a pure online shooter. Fast paced action, multiple game modes, superb level design and a plethora of weaponry made this game sublime. I still remember getting my first "M-M-M-MONSTER KILL!" whilst sniping on Facing Worlds, and jumping around on Morpheus with dual pistols as if it was The Matrix; it was brilliant! Unreal Engine and Epic would never have been so big if it hadn't been for this game's success.