A homebrew is an unauthorized port of a video game to a hardware platform that requires the use of a proprietary storage method, such as a cartridge or console-specific disc format.
Given its popularity and the fact that its source code is publicly available, Duke Nukem 3D has been the subject of at least one homebrew and several unauthorized ports to other platforms.
After the source code for Duke Nukem 3D was made publicly available by 3D Realms in early 2003, the game's first homebrew appeared within months. Duke Nukem 3D and the official expansion Duke It Out In D.C. were ported to the Sega Dreamcast in May 2003. The port has a very low frame rate and is generally considered poor quality.