Hey! I really enjoyed this! I was skeptical during the first phase of the boss fight, but the game really scaled up! I was surprised that you managed to get 3 phases into the fight, and appreciated having hard mode after I finished it. A nice treat for those who stick with it. I love that you included a screenshot of your sprite sheet, that's super cool!
I had a lot of fun with this one. I don't know that there's much room for critique. The art was good, the gameplay was good and fair. I wish there was some content other than the boss fight, but there was a tutorial, which was nice. All in all, a very clean and well done game jam game. Way to go!