Really unique game! Music, sfx, and visuals are polished really well. Overall game feels really nice to play and is very intuitive and lets you figure things out. Discovering mechanics on the go was pretty satisfying, such as learning to use the gymbags to tank fire.
The boss fight feels a little too difficult but perhaps it's a skill issue. I think it could be interesting if more of the items were incorporated into the final boss fight.
Small Note:
Resetting the level with R seems to break the game at least in the WebGL version. Clicking on the level in the left menu selection to reset it works fine though.