Using ZDoom on UV. Good map. Good use of height. I've always liked maps where you criss-cross the same areas from different directions at different heights just using standard architecture, without 3D bridges and such.
The references to 'Nirvana' are nice, as is the great ambient/trance music, but I'm not sure the duplicated second copy of the opening rooms is necessary. It didn't feel like a 'twisted-hellish-version' of the original, just a harder version. But the teleport destination sectors in the secret areas should all be monster blocked (sectors tagged 8, 28, 10, 27, 17, etc). I telefragged a Shotgunner or Chaingunner almost every time I landed.
Linedef tag 2 teleport linedefs should be tagged as monster block. I telefragged a Caco that wandered into it, since the teleport destination in the main room has its linedefs (tag 1) tagged as monster block.
The Yellow Key bar sectors are not joined. I was able to open one of the bars and leave the others closed. That meant I was able to go through but the Mancs and the Arachno couldn't follow me. Is that considered smart gameplay or just taking advantage of the monsters' large size?
The Cyber past the Red Key door - There's enough room between the bars to shoot him and enough distance from the bars so the splash from his rockets hitting the bars doesn't affect you. I killed him with my Pistol. I used all my Bullets, then kept going back to find more ammo until he died. I was going to suggest some sort of transparent barrier instead of bars, but then I found the teleport which would have telefragged him without firing a shot. So it was all a huge trap to waste ammo. That's just evil.
The exit room - Chaingunners shooting at you from a huge distance is always annoying. You can't seen them, can't hear them shooting, no idea where they are; while you take damage. Good thing there weren't too many of them. The SpiderBoss died before I could shoot her. I was taking care of the AVs and I heard her die. Don't know if she got stuck on the wood sectors in front of the exit when she teleported in or if she couldn't move enough because of the monster block linedefs surrounding her.
I don't gamma-adjust, so a little dark in places, but otherwise, fun. Very nice work.