Wolfenstein: Enemy Territory

Wolfenstein: Enemy Territory is a free and open-source multiplayer first-person shooter video game within the Wolfenstein series. It was originally planned to be released as a commercial expansion pack to Return to Castle Wolfenstein and later as a standalone game. However, due to problems with the single-player aspect, the multiplayer portion was released on 29 May 2003 as a freeware standalone game. In January 2004, the source code for the game logic (not the game engine) was released to the benefit of its modding community. The game uses a modified Return to Castle Wolfenstein engine, itself being a heavily modified id Tech 3 engine, which has been open source since 2005. As of the first day of the August 2010 QuakeCon, the entire source code was released under the GNU General Public License v3.0 or later. The media assets remain proprietary. On April 26, 2022, the game was released on Steam, and on October 20, 2022 on gog.com. A commercially released follow-up, Enemy Territory: Quake Wars, was developed by Splash Damage.