I found the game quite difficult and found that the hammer wasn't really worth using compared to timing the electric shock properly. I don't know if I miss understood the game or something but the hammer felt useless in comparison to the shock.
I would also say there should be more particles or visual indication as well as a cool sound effect when you land right on the beat as its a bit hard to tell other than by looking at the extra points you got. You could probably do this on the baseline like where the heart beat is and like scale it up and have some particles for some extra juice!
Other than that, really good entry I enjoyed playing!