The speed and fluidity of the gameplay is really nice! Very well executed!
The progression is just a bit slow in comparison. (One too many rooms per floor and one too much added HP to enemies on subsequent floors) I would love to push for an all Rockets or Ricochet build, but the difficulty/stats ramp has started to become a time sink.
A minor frustration I had was being trapped in a corner (usually the entry door) by a group of the melee guys. I suggest giving the player a kind of Push Back melee attack to help make space.
One more addition could be HP bars on the enemies, it would help with moment to moment decision making (finding the best target for your current bullet) on top of spamming the shots (witch is also fun).
The style is great and grounds the world!
All the systems work very well and are well balances (speeds, shots, level design, movement).
Definitely a great little project, you guys should be proud!
I had good fun with it!