Tremulous: FPS with elements of RTS

Tremulous is a first person shooter with elements of real time strategy. The game was realeased in 2006 and has become very popular. There are two teams, humans and aliens. The goal of the game is to destroy the others base and kill of your enemy. The graphics are great and the game play is fun. The game works well on Linux. It is a free and open source game. There is a nice video available here.