Woah, this is super cool! Firing the chain gun feels very satisfying. I think you really nailed that dakka dakka dakka feeling. Also my favorite feature, the missile parry kick. That stuff is great, I loved doing that on the final boss especially, that was awesome. The brass platforms slowly rising was fun, felt like an assurance that you can always progress even if platforming fails.
Aesthetically everything fits together well I think. The art, the effects, it all gave that intense high-action shooter vibe. Maybe it could be a bit faster overall? But then again maybe I'm just bad at games and you can move faster when you play better. Yeah, thinking about it again, it might be that, for example I also never really managed to get the sideways spirit form going by building momentum, that looks super fun from the screenshots, just blazing through enemies.
But these are minor things, you really have a super fun game here!