Extremely solid and well made game all around. Not much I can say
Presentation's amazing. Although I feel like the projectiles in the mermaid boss could've stood out from the environment more. They blended a little too much imo
The concept is amazing and I love how you managed to make every boss feel varied.
I like the idea of your super bar filling faster depending on your distance from the boss. Personally, I never really made use of it, but I can definitely see speedrunners or score chasers using it though. A pretty cool way to choose your own difficulty so to speak.
I have only one real issue, and that is that I couldn't really get an accurate feel on how big my hitbox was. Sometimes it felt like bullets just passed right through me, and other times it felt like I got hit even though I shouldn't have. ( Probably just a skill issue )
Apart from that though, I genuinely don't have much to say or criticise on this one. It's lean, mean, well paced and the difficulty is near perfect.