Really creative idea! I love the very Genesis/Megadrive style sprites. It's an interesting design decision to tie player health to "mana" essentially. I found it a little irritating to be honest but that doesn't mean it's a bad thing. I killed myself twice on the first level before I realized. XD
I loved the way the enemy health bars would indicate how much damage you would do as your charged up a chord. super satisfying to chain together three or four quick kills in a row.
Great work!