Free Game With Great Graphic And Lots Of Mutators...

Cross-platform, open source FPS built on the Cube 2 Engine.

Red Eclipse 1.4

Red Eclipse is a multi-platform, free, and open source first-person shooter that runs on top of the Cube 2 Engine. It has six different game modes: Campaign, Deathmatch, Capture the Flag, Defend the Flag, Bomber and Time-Trial.