Using Rube Goldberg machines as a concept for this was great! I like the overall mechanic where you take advantage of the pieces' pivot points/other marbles to help move the marble to the goal. One feedback I can give is to show some sort of visual feedback (like highlighting) when hovering the pieces over pegs so it's clear that the piece can fit there (without having to click to check). Other than that, the music's great, and the overall aesthetic is pretty nice.:D