http://www.boswars.org/index.shtml
I'll take the honor of posting the first actual game post thanks Droope
I've been waiting for along time to post this, so it seems fitting such the Open Source RTS should have the honors 
(If anybody knows of another famous Linux RTS let me know)Bos Wars is a futuristic real time strategy game (RTS). In a RTS game, the player has to combat his enemies while developing his war economy. Everything runs in real-time, as opposed to turn-based games where the player always has to wait for his turn. The trick is to balance the effort put into building his economy and building an army to defend and attack the enemies.
Bos Wars has a dynamic rate based economy. Energy is produced by power plants and magma gets pumped from hot spots. Buildings and mobile units are also built at a continuous rate. Control of larger parts of the map creates the potential to increase your economy throughput. Holding key points like roads and passages allow for different strategies.
It is possible to play against human opponents over LAN, internet, or against the computer. Bos Wars successfully runs under Linux, MS Windows, BSD, and Mac OS X.
Extract where ever you want and click "boswars" to play
Requirements
None! I'm only not certain as to what's the lowest processor speed required to play this game
Edit: Requires SDL
