I dont know how many 3d games are for 68k but they are at least
blitzquake
beastieworker
gltron
payback
glsokoban
apoolgl
cube
FPSE (playstation emulator with lots of very enjoyable 3d games)
descent
tuxracer
117
...
and certainly others small games or quake variants that I have forgotten
There is also the GLeXcess scene demo that is not a game but nice
Also my Microbe3D.library exists for 68k : it is not a game but a nice 3D engine
Alain Thellier
Note: Can see here some grabs of those games
http://thellier.free.fr/Wazp3D.htm