You can find the source in their git here.
Games include:
Catacomb, The Catacomb, Catacomb 3D, Catacomb Abyss, and Hovertank3D
However this does not include the data files (of course). Â Also this is not 100% of the source code, as I noticed that libraries are required.
I haven’t taken too much of a deep look though.
The Cat Abyss code works! But, YOU MUST have the version from 12-2-93. Was getting all kinds of memory allocation errors trying to get it to start, after much printf sprinkling I ended up at the GFX header that was generated with IGRAB for where the chunks are located in EGAGRAPH.
Anyways, here it is: http://dk.toastednet.org/Cat_Abys.7z