Unreal Tournament is one of the best multiplayer games of it's time. When Quake was dominating the online scene, this gem unexpectedly blew Quake 3 Arena out of the water. With a focus on team play and several innovative game modes it became an instant classic. Few can deny how fun it is to storm a beach or fight in Earth orbit. This game has spawned 3 sequels and the only one to exceed this one is Unreal Tournament 2004. It's also available at this site and is worth checking out.