NEXTSTEP

At the time of Doom's production, id Software was using a for its graphic engine development, so the  version of Doom actually existed before the MS-DOS version. The application is sluggish on anything other than an -based NeXTstation or NeXTcube (the more memory, the better), and has no sound support. With OPENSTEP on the most recent x86 hardware, it runs smoothly under all conditions up to screen sizes of 400%. The released version is labeled v1.2, with programming credited to John Carmack, John Romero, and Dave Taylor.

Trivia
Quake and Wolfenstein 3D were also first developed on NeXT hardware.