Thanks HonestDan. I agree, there is no shame in using Assets. If I were a studio I would have a budget for for staff to build this stuff, but for a prototype just throw them in and do something cool, if it works then expand and improve on them. Of course, the trick is to use them in creative ways rather than just flip them.
I totally agree about feedback in the rhythm game. Maybe some camera shake when you miss a note and visible “pop” on the note if you hit.