This level can be somewhat tough, considering that if you don't find the (very well-hidden) single-barrel shotgun, you'll have to get around with just the pistol.
Interesting things to note in this level are a drainable toxic waste pit, a conveyor belt maze, a crumbling corridor, and a lot of colored lighting like in the PSone Doom games.
Credits:
id Software, Randy Heit, CodeImp, and everybody else
Base:
New from scratch
Build time:
about 56 hours, including thinking and taking breaks