Apparently the lead programmer released much of the source code a few years ago here https://github.com/RandalLinden/DOOM-FX

But it was uncompilable because of copyrighted assets/code. This seems to be the full source which includes the missing stuff.

Actual source files seem to be here https://ia600408.us.archive.org/view_archive.php?archive=/3/...

The backstory for the 3DO port of Doom[0] later in that thread is crazy! Worst sales/negotiation ever.

[0] https://gbatemp.net/threads/doom-for-snes-full-source-code-r...

This was an incredible port, and certainly an engineering masterpiece given the target hardware.

The level geometry of this version was more complex than the PlayStation port, and it even had online multiplayer support.

One interesting difference though is that enemy sprites only face the player.