I really hope this game gets more traction because the idea is absolutely phenomenal. If you were looking to develop this game further, I would recommend adding some pitch variation to the notes to make it sound a little less monotonous and to add a short, looping track for the beats to go along with. I did also notice you had a problem with the character facing down and left whenever there wasn't an input detected. I'm not sure how it works in Unity, but in Godot, you can fix this by creating a variable that keeps track of which direction you're facing and only update that variable when an input is detected. I hope this helps!