This is so awesome! Everything flows smoothly and naturally. I love how every attack is telegraphed (even with the placeholder sprites) and with each game over and restart it makes you feel like you're getting better instead of frustrated. Plz nerf the ice puck attack because once you discover it, the fight at any difficulty becomes a matter of waiting for a downtime in the attacks and spamming down +X/Y really fast.
I can't wait to see more bosses! Keep it up!