Thanks so much for the feedback! I couldn't get the beat to sync up properly unless I used a very loud audio clip. The multiplier actually goes up and down on every action, so the idea was to get them to click, and tap spacebar to the beat while moving it to the grid.
Also, the pieces aren't actually meant to fit properly. You can fit corner pieces in the middle.
Thanks for your suggestions though! If I were to develop this further I'll definitely come back to this. In the mean time, I'll have a go at your game.