Good game. Didn't realise that it was procedurally generated each time you play until I accidently pressed esc and went back to the main menu. (This should probably have a confirmation).
The flying enemies were good. The others were just rude, they would just drop from the roof and cause seemingly unavoidable damage.
The jetpack should probably be bound to something other than space. I ran out by accident when trying to jump on ghosts.
Using enemies to jump to higher places is a neat idea, it didn't really seem well executed as I found it easier to not bother.
Misc notes: The art was nice. I like that you fell to the bottom when you died. Didn't realise that I had dropped the key when I died, actually died on purpose once I had the key to get to the bottom, made it to the door, then realised I didn't have the key anymore.
All in all, good job.