Catacomb 3-D is the Wolf3D's ancestor, so the engine is quite a bit more primitive (16 colors, running into a wall at an angle stops you dead so you're constantly stuck, etc). In my opinion, it's not worth mapping. Catacomb Abyss, Catacomb Armageddon and Catacomb Apocalypse use the same engine although I haven't played any of them.
I've never played Ken's Labyrinth either, but it looks like it uses an improved version of the Wolf3D engine.
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Current projects: Bucky O'Hare (NES), Metal Storm (NES), Clock Tower (SNES), Ristar-The Shooting Star (Gen), Sonic The Hedgehog (Gen), Sonic CD (Sega CD), Mega Man Zero (GBA), Battletoads (NES)