Sauerbraten is a free, multiplayer/singleplayer first-person shooter (FPS), built as a major redesign of the Cube FPS. Much like the original Cube, the aim of this game is not necessarily to produce the most features and eye candy possible, but rather to allow map/geometry editing to be done dynamically in-game, and to create fun gameplay and an elegant engine.

The engine supporting the game is entirely original in code and design, and its code is Open Source (ZLIB license, read the docs for more on how you can use the engine).

In addition to the FPS game which is in a very playable state, the engine is being used for an RPG which is in the preproduction phase.