pretty fun, just a few minor criticisms.
the arena is a bit big for how many monsters spawn in it, and the spawners could possibly do to be a bit more spread out rather than just on the edge
from what I've seen, shotgun ammo just doesn't appear, and rocket ammo is scarce while cell ammo seems to be absolutely everywhere. megaspheres are also a little bit common, so there isn't much challenge, and I figure it'd be more engaging if pickups spawned throughout the map.
I'm a big fan of the big ol hoards of imps, especially when I get to rocket them, and likewise with the caco clouds and the bfg. overall very entertaining, large hoards of enemies are always satisfying to mow down
