BZFlag is a 3D multi-player tank battle game that allows users to play
against each other in a networked environment. There are five teams:
red, green, blue, purple and rogue (rogue tanks are black). Destroying a
player on another team scores a win, while being destroyed or destroying
a teammate scores a loss. Rogues have no teammates (not even other
rogues), so they cannot shoot teammates and they do not have a team
score. 

There are two main styles of play: capture-the-flag and free-for-all. In
capture-the-flag, each team (except rogues) has a team base and each
team with at least one player has a team flag.  The object is to capture
an enemy team's flag by bringing it to your team's base. This destroys
every player on the captured team, subtracts one from that team's score,
and adds one to your team's score. In free-for-all, there are no team
flags or team bases. The object is simply to get as high a score as
possible.

WWW: http://BZFlag.org/
