Very well done!
Concept was original and well executed! Loved the boss battle too.
Nothing bug related, but the only feedback I could give here is the art style clashes a little bit, you have pixel art and clean line "vector" art in the same scenes, it feels a little bit slapped together. Also the pivot point for the head feels slightly odd and unnatural being centered on the hat top button, I'd suggest dropping it just slightly so it feels more like he's turning at the neck, in a purely top-down perspective this would work fine, but the perspective is angled so it feels less organic.
Otherwise this was a really solid prototype and works well!