Nice game, but a little more feedback for getting the right notes would be fun, also the audio is only coming from the left.
Since you used Godot I assume you've used an AudioStreamPlayer2D, this node plays the sound from where it is coming from, which is very useful for listening to npc movement and following sources of sound, but for music you generally want to use an AudioStreamPlayer node instead, specially in your case since there is no sound at all coming from the right.