Very well made game, great work!
The sound effects felt a bit too loud and some way to see your health would have been nice, but those are my only real criticisms. Otherwise the game is very well put together. There's an astonishing amount going on for just one room, and I never felt lost while playing. The colour palette and pixel art looks great.
I also found the gun upgrade hilarious. Complete subversion of expectations in the best way possible.