The Doom rendering engine is the core of the game engine that powers Doom and its sequels, and that is used as a base to power other games by id Software licensees, notably Heretic, Hexen, and Strife. It was created by John Carmack, with auxiliary functions written by John Romero, Dave Taylor, and Paul Radek. Originally developed on NeXT computers, it was ported to DOS for Doom's initial release, and later ported to several other operating systems and game consoles.