Try to recreate the image with a limited number of moves. Click and drag your mouse on the squares to brighten or darken them. There are three types of moves:

- The add move adds light to each square.
- The subtract move always makes squares dark.
- The multiply move swaps them, so if the square was dark, it will brighten, and vice versa.

Pay attention to the moves that you have on the right side of the screen! Warning: the later levels are really hard!