BZFlag is a massively multiplayer networked tank-shooting game plays like a cross between 'Battlezone' and 'Tank Battle'. Players drive around an arena and blast other enemy tanks. The 3D is much enhanced from BattleZone in terms of looks and gamplay (features a multi-tiered battle arena). Here the tanks can jump. Tanks can enhance armaments or gain new fighting abilities by capturing 'power-up' flags littered around the playing field. Simple premise that rapidly becomes addicitive. Good fun.
Version 2.4.2: Release notes were unavailable when this listing was updated.