A huge, sprawling 5-D space level. Very easy to get lost, lots of narrow passageways. (You can use wall textures to help you navigate, until you run into that infrared powerup...)
Looks like it was designed as a solo level, but it's so small, it would make a better net level. Really sharp edges, and one bad (but non-fatal) texture. Ammo placement leads me to believe it was designed to be played on Kindegarten.