Sauerbraten (also known as Cube 2 or Sauer, German for “sour roast”) is a cross-platform, Quake-like, first-person shooter computer game that runs on Microsoft Windows, Linux, FreeBSD and Mac OS X using OpenGL and SDL. The game features single-player and multiplayer game play and contains an in-game level editor, its main feature. The game engine is free and open source software, under the Zlib License, with commercial support available from the developer's own business counterpart, Dot3 Labs.
The game started as a redesign to the original Cube Engine, and its first release was made on May 6, 2004. The latest release, dubbed the "CTF Edition", debuted on June 17, 2008.