I'm not sure if the source was available before. But if so, I'm wondering if anyone has compared it to the original source to see what was changed? Anything interesting? Anything major?
yes, id software is notorious for open sourcing all their games a while after release.
John Carmack took a few months break from Rage development to work on these (at least on Wolfenstein, not sure about Doom) [1], so there will definitely be substantial differences to adapt to iOS, like - I'm guessing - OpenGL-ES code and touch controls.
Great little detail:"Wolfenstein was originally written in Borland C and TASM for DOS, but I had open sourced the code long ago, and there were several projects that had updated the original code to work on OpenGL and modern operating systems. "
Everyone benefits from Open Source, even the original creators.
Don't forget idspispopd for noclip (Doom 1). I must have typed those cheats a thousand times. If you tried using Doom cheats in Heretic you'd get the opposite effect. idkfa would strip you of all weapons and iddqd would kill you. Great addition to the game!