Nice idea! Sound effects are cool too. Perhaps you could add more environment to interact with, e.g. non-destructible stones, because at some point the winning strategy becomes just luring the enemies to insanely bouncing head :) There are couple of minor bugs - first, the head sometimes gets stuck, and second - there's some weird game state after you die, you can shoot a lot of heads at the same time, the heads bounce off enemies but do no damage. Still, great game, I enjoyed it :)
Feel free to check out my take on the roguelike genre: https://itch.io/jam/gmtk-2019/rate/460262