Brother left to go home so I had some time to check this out.
Game play is fun and the alien/ammo/health ratio is good
creative layout and design
design wise though, you should fix two things about the ceiling crushing area:
even though you want to leave it as is for speed running, you should change it so it can't be passed so easily, lower the ceiling so the jump can
only be made by strafe-jumping, also give the player a way to get out of the lava pit if they fall in
another design fix: the lava whirlpool was pretty cool, but you should smooth out the sector work so it isn't so choppy
texturing is good and fits, improve the shading, add some detailing and trim work to give the map more depth and a more immersible feel, as it is
now, it feels kind of generic
Overall it's a pretty solid map, especially for a first release
