http://doom.wikia.com/wiki/Doom_source_code http://doom.wikia.com/wiki/Doom_source_code (john carmack et al - you may be able to find which parts carmack wrote

http://doom.wikia.com/wiki/Doom_source_code http://doom.wikia.com/wiki/Doom_source_code (john carmack et al - you may be able to find which parts carmack wrote from articles or code comments; apparently there's a commit log too)