1. Click boxes to find the diamond, if you clicked the box that contained the diamond, you win. You have 4 chances to try. If you clicked a wrong box, it would show the DISTANCE between the box and the diamond.
2. The DISTANCE is the count of boxes through the "SHORTEST, RIGHT ANGLE" way from it to the diamond box. As the figure shown, the clicked box displayed 3, the diamond around shows all the boxes has a DISTANCE of 3, so they are the possible positions that has diamond.
3. As shown, when calculate the DISTANCE, you can go through the edge.