People like Fabien Sanglard

id Tech 1, also known as the Doom engine, is the game engine used in the id Software video games Doom and Doom II: Hell on Earth. It is also used in Heretic, Hexen: Beyond Heretic, Strife: Quest for the Sigil, Hacx: Twitch 'n Kill, Freedoom, and other games produced by licensees. It was created by John Carmack, with auxiliary functions written by Mike Abrash, John Romero, Dave Taylor, and Paul Radek. Originally developed on NeXT computers, it was ported to MS-DOS and compatible operating systems for Doom's initial release and was later ported to several game consoles and operating systems.