Personally I rate Alien Breed 3D as one of the finest.
Blocky it may have been but it got the atmosphere right :-)
Pity there was never a c2p version. That could have run quite well...
TKG was extremely good in terms of appearence IMHO, but was just too sluggish. I had a lot of fun creating models and playing with some third party level editor (cant recall the name).
My mates cyberstorm Mk III ran it reasonably well though.
