In this game you are to find a code of different colors in a 3x3 layout.
For each attempt, you are granted a black key for each color in the the right position, a red key for each color in the right row, a yellow key for each color in the right column, and a white key for each color that must be moved both horizontally and vertically to get in the right position.
Further explantions and examples are available in the help section of the game itself for which there is also an option for a free download.