It was a pretty fun game. The boss was a bit difficult until I realized that I needed to break the hearts with a dash and that having a speed upgrade helps with dodging the bullets.
I really like dashing through the enemies for an easy kill while putting yourself at risk vs using the dash as an evasive maneuver while shooting bullets. The red charging enemies where a bit annoying to deal with when the screen is zoomed in at the start of every run, but overall I had a good time playing your game :)