Good idea! Any thoughts of making the motions of the spheres synchronized to some rhythm or some modifications in physics so to snap the landing positions on to the keys?
Update: The audio design works well for this game. It might sounds better if there is a internal compressor for all those sound effects, since one can easily stack a lot of the spheres on stage.
Thanks! Actually, I want the game to be a bit chaotic (kind of like a pinball), so I prefer to keep the physics of the spheres untouched. However, using a compressor is a good idea! I rarely use those, but it seems indeed appropriate for this game. I might try to implement that.