Yeah, it is the original level editor for doom. It ran on NeXT. Many people built separate implementations, based on the reverse engineered wad format. Doombuil

Yeah, it is the original level editor for doom. It ran on NeXT. Many people built separate implementations, based on the reverse engineered wad format. Doombuilder, Slade, etc are examples. There's even one named 'DoomEd', it is, however, not related to the original, never-released one from id. http://doomwiki.org/wiki/DoomEd http://doomwiki.org/wiki/DoomEd Thanks for your answer, so it really seems the sources never made it out of id. :(