Very good job on the theme, it was fun to play it, my first all 5 game :). UI-wise was a bit strange to see quit button in settings menu :D and that you have 2 fullscreen options: from unity and itch.io one, when itch.io one doesn't work properly, so perhaps you need to disable it, cuz they are almost in the same place on the screen. Balance-wise, it felt a bit unfair, when first boss spawned his blue circles such way, that you can't escape it, for example when safe spot in the opposite direction, so even with fast speed you can't go there in time.
But nevertheless, again, good work, it felt like I was playing steam-release-ready game.