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 "".
ShadowCaster
The "ShadowCaster" game engine, a successor of the "Wolfenstein 3D" engine and a predecessor of the "Doom" engine, was written by id Software's John Carmack and licensed to Raven Software. Carmack wrote the "ShadowCaster" 3D engine during his technology research after id Software completed "Wolfenstein 3D". The engine features diminished lighting, texture-mapped floors and ceilings, walls with variable heights and sloped floors. The engine was "about half as fast as that of "Wolfenstein"" but fit the exploration of "ShadowCaster" rather than the fast-paced action of "Doom".