Fill all of empty squares in the grid with a picture. Each picture may appear only once in each row, column, and 3x3 box. Each puzzle has only one solution. If you get stuck, you can click the 'give me a hint' button and any errors you have made will be highlighted in red; or if you've made no mistakes, a green square will show where you can go next. If you try to place a picture where it already exists on that row, column, or small square, both occurrences will be highlighted in red.