Red Eclipse

 
Red Eclipse is a single-player and multi-player first-person ego-shooter, built as a total conversion of Cube Engine 2, which lends itself toward a balanced gameplay, completely at the control of map makers, while maintaining a general theme of agility in a variety of environments.
The project is a Free and Open Source game, built on Cube Engine 2 using SDL and OpenGL which allows it to be ported to many platforms; you can download a package for Windows, Linux/BSD, Mac OSX, or grab a development copy from our Subversion repository and live on the bleeding edge.