Team based Aliens vs Humans FPS with buildable structures.
An old game, and still a great game, hopeless development team. MG dev team have done very little except make lots of promises and very little updating in many years. This game needs to be forked, and done properly, but so far that hasn't worked well because the Tremulous community has got to be among the most troll-overpopulated of any Quake-type game that I have EVER come across. Keep off the main Tremulous.net forums, and just go to one of the clan forums or other server forums instead if you want to meet nice people.