As others have said, really felt like a page out of id's ep3 book. A good page!
Played through on skill 3, all kills, all secrets. The only secret I missed the first time through was the MH, eventually found it after I reached the end and came back through. I liked how you looped and reused space. It wasn't a super short level, but once you reach the end you can backtrack anywhere else in the level in just a few seconds.
The only monster encounter I had difficulty with were the vores in the GK arena. My quad had faded when I picked up the key and since they spawn on the outside ring, you almost inevitably get hit a few times (at least in skill 3) as you try to make it back to the outside for cover. Died once when I incurred a trail of 4-5 vore balls and fell into the lava.
Great level!
Demo