I will work on refining the rules and messaging on them. Right now, the feedback is limited on failure, so I wish I could show more useful feedback than this column is wrong. The Xs block of certain grid spaces for pieces, but each rotated position of a piece is actually unique so you have to listen to correctly deduce the proper placement. That said, I'll do another pass for balance and to avoid common errors. One tutorial step I might add is how to determine if two parts of a song go together. Ex. two conflicting vocal tracks can't stack.