I really like the classic NES feel this game has. From the sprites to the music and the simple gameplay loop, you could put this game on an NES rom and I would think this was a hidden gem for the console that no one has discovered yet.
The only thing though is that when I die from the enemies and arrows, for some reason the wave just keeps going and I proceed to the next wave even though I should've lost. But overall, I think you did a pretty good job with this!