Attain the highest possible score by removing as many rows as possible. Any horizontal, vertical or diagonal line of three images disappears immediatly, and the pieces above fall down. New images are falling in the playing field from the top, as well. If the falling pieces form a line as well, it is removed too, and it is also added to your score.
You can form a line by swapping two images that are horizontally or vertically next to each other. First click on the one first of the pieces that you want to swap and then on the second. You may swap two pieces only to form a new line.
The game is finished when you can not form a new line by swapping two pieces.