Wolfenstein 3D
Although id Software did not develop another "Wolfenstein" game, as their development focus shifted to "Doom" shortly after release, and has never returned to the series, multiple "Wolfenstein" titles have been produced by other companies, sometimes using game engines developed by id. The first of these newer "Wolfenstein" games was "Return to Castle Wolfenstein" in 2001, a reboot of the series, and the latest is the 2017 "".
Return to Castle Wolfenstein
The source code for "Return to Castle Wolfenstein" and "Enemy Territory" was released under the GNU General Public License (GPL) on August 12, 2010. The "ioquake3" developers at icculus.org announced the start of respective engine projects soon after.