I played the game and wow - just as I thought I was at the end, you managed to have even more gameplay! It took me about 30 minutes to beat it.
I love the music - the art is nice as well. The movement though is probably the thing I like the most - it feels very fluid and the confine mode feels great. (Also quite fun with 3 clones and holding down LMB. Makes it a contest of seeing if I can lag out my PC!)
I did encounter a couple bugs later in the game, around wave 15.
For some reason after I got the skip-basic-demon item sometime around that wave, the next two waves just didn't spawn. I went into confine mode on wave 17 - 18 and then they seemed to instantiate a dozen or so seconds later.
I also found a demon-guy who went out of bounds on one of the teen waves near the top-side of the map! But, I was able to kill him by changing my angle weirdly enough - even though he was outside the wall.