This is really cool. I think I would've liked just a little more to explore after getting the breath attack, but what's here is just a solid bit of fun. I find all the sound effects to be very satisfying, especially when damaging enemies. There's something about that slightly muted thud that just makes defeating enemies feel very fulfilling to me. The breath attack is cool, if a little under utilized. It took me a second to figure out the timing of it, though. The sound cue can be a little quiet in the heat of battle and the visual cue can be a little subtle between the start and end of it even when paying attention to it until you really get used to it, so it was hard to judge when I was done charging at first. I think maybe having a little white orb pop up in front of the player at the end of the charge or having the ring on the players head become a solid red/white color could help in that regard to more immediately indicate "hey, you can fire now".
Outside of that though, it was pretty fun. Didn't feel too difficult, the boss fight was nice and fluid for the movement options available to you, and the more atmospheric music was pleasant and provided a rather calming vibe to me as I dashed through the foes who have invaded my home. Well, I assume its my home. and even if it's not, it is now. Not like they could stop me. All and all, good work on releasing the game despite the circumstances you were under!