-Not much to say, I've played this several times as Mario Party minigames. The one thing I find neat is applying a musical note, so it works well for people who remember tone better than visuals. With expansion, it could be a decent game.
-Clicking the same note quickly will cut the previous sound short, or sometimes won't play the second one at all it seems.
-Having the damage take place after the gameplay feels needlessly long, I would display the damage as you press the blocks to expedite it.
-If you lose HP, on the next battle it will also lower your max HP to match, which seems wrong.
-There seems to be no reason to go back to the entrance, you lose HP but have to start from the beginning.