Ok, this was way more entertaining then I would have guessed just looking at it.
Controls were good and the exploding sounds were VERY satisfying. Reminded me a lot of playing games on he Game Boy (the OG grey one).
Endless mode needs some work though, the health is not capped so you keep getting more and more health (I got to 11/3 health) and when I got to 31 kills the whole level just disappeared :P Also the difficulty should ramp up a bit otherwise endless really is endless.
Great job !