Following the successful release of Wolfenstein 3D in May 1992, most of the id Software team worked on the sequel, Spear of Destiny. Since this game used the same engine as Wolfenstein, lead programmer John Carmack could use the time to begin work on the company's next-generation graphics engine. With significant effort, choosing to isolate himself from the rest of the team for a long period of time in order to avoid distractions, he implemented various new features, including varying light levels and texture-mapped floors and ceilings. He even added support for sloping floors, although this feature was later removed. The engine was not developed with Doom in mind, and in fact Doom was not the first game to make use of it: Raven Software licensed an early version for Shadowcaster, which wo