Hey, I just played your game.
I think I found a bug, when you spam space while respawning the player sometimes gets stuck in the air. Also when smashing on top of the boss I sometimes died instead of damaging the boss.
Smashing enemies is pretty satisfying. This would really be a neat little game if just the restarting didn't take so long. The player needs to be able to respawn on the press of a button when you have instant death spikes all throughout the level. Otherwise it just turns frustrating.