Summary: the LAB3D-SDL-2.32 binary didn't work on my 64-bit machine, so I compiled the source code and it works like a charm on GNU/Linux \o/
Ken's Labyrinth has been my favorite FPS right from the start, because this is the only FPS I can win *without* cheating.
I purchased Ken's Labyrinth 2.1 via Compuserve's SWREG. And had a lot of fun.
Unfortunately it didn't ran under Windows 9x and above. So I was very surprised and happy to learn about the Official Ken's Labyrinth Page, which provides links to 32-bit ports for "Modern Operating Systems".
The LAB3D-SDL port worked fine on 32-bit machines, yet refuses to run on 64-bit machines.
I simply replaced the original 32-bit binary with the fresh compiled 64-bit version in the ~/ken directory and it works like a charm <3