Even if the overall feel can be improved, It's a pretty cool minimalistic metroidvania.
As a masochist I decided to play on the hardest difficulty and I managed to kill the first boss, if only there was saving I would continue it but maybe for the next build.
Other than that, I think the dash/attack ability is kind of unintuitive and frustrating, I don't know if that's intentional, but if not you should consider having one button to attack (shoots in the last direction you walked) and one for dash (shoots in the opposite of the last direction you walked) instead of having one for right and one for left