Each row, column and tinted square set must have one and only one of each number, character or sushi piece. There are 3 tile sets, you can pick which one is more suitable for you. If you get stuck, there are 3 hints you can use. Using hints costs an additional 2 minutes. There is also an undo button if you made a mistake. Use YOUR MOUSE and click on the piece you would like to put down on the set on the right. You can also use the keyboard 1-9 NUMBER KEYS. And then click on the square where you want to place that piece. Check in-game help to fing out how to delete a piece, use pencil marks or get some hints. Have fun!