Warsow is a standalone multiplayer game.  It features:

  * 3D Engine based on Qfusion (a modification of Quake II GPL engine)
  * eSport oriented FPS
  * Fast-paced gameplay focused on trix (trick jumps) and art of move
  * Complete Power-up System including Weak and Strong fire mode for each
    weapon
  * Cartoonish graphics with celshading-like-but-not-Manga style, mixing
    dark, flashy, and dirty textures, matching with action full of fun
    and speed

WWW: http://www.warsow.net/