/vr/ - Retro Games

Rise of the Triad contains code taken from Wolfenstein 3D, as well as early versions of the Zone memory and WAD file systems from the Doom source code. It also makes use of an early version of Doom's patch_t image format which is close to that used in the press release beta version, indicating that Hall's team was given access to an early transitional source base, perhaps related closely to other contemporary games such as Shadowcaster.[1]

Oddly, the same zone and WAD file code, further modified, also found its way into the source code for Duke Nukem 3D, quite possibly in violation of its original licensing terms. id Software is not known to have ever taken any legal action in regard to this possible misuse, however.