Anyway, START THE PARADE!
Trooper
Wolfenstein SS
Lost Soul
Imp
Sergeant
Demon
Spectre
Cacodemon
Commando
Hell Knight
Revenant
Pain Elemental
Arachnotron
Mancubus
Baron of Hell
Arch-Vile
Spider Mastermind
Cyberdemon
As much as I'd like to work on the monsters, I have to fix the rendering code. Right now I'm lucky to get over 5 FPS on most levels, taking those screenshots took forever.
As for the low framerates, it sounds to me like you're going to need to introduce somesort of beefy culling algorithm or somesort. Perhaps a BSP tree would work?
Regarding the Spectre demon enemy: do you plan on just leaving this enemy flavour just transparent, or will we see somesort of cool black-pixely effect on them like the original did? Was this even a dynamic effect, or is there an animation in there for them? Aside from shaders (way outside my realm of knowledge :P), I'm not sure how you could implement this efficiently inside the fixed-function pipeline. :-/