Very cool game! It was a bit hard to get into it, but once I understood everything, it turned out to be quite fun!
I'd like an indication of what input you have selected. I also think it would help the game a lot if the health wasn't affected once the wave left the screen on the left, but immediately when you deform the wave by subtracting. That way, you'd immediately know that you did good or poorly.
Interesting concept, good job!