This gets almost full marks from me, this is genuinely a really great game! Admittedly I haven't been able to beat the boss because I use a 65% keyboard and so my arrow keys are on a different layer than the other buttons, so moving and jumping or dashing have to be distinct inputs and it's hard to switch between them in an instant. At first I had a bit of trouble adjusting, but later on I found just how much of the game I could traverse just by jumping and dashing. I'm a sucker for games like this that feel a lot like Megaman.
If I had anything to critique, I think it would just be the visual communication of damaging enemies. You feel like you're dashing blindly into regular enemies and unsure if you're even hitting them at all, and adding a quick flash to the sprite would easily fix that.
Absolutely phenomenal job!!!