The object of the puzzle is to reverse the positions of the black stones and the white stones. The red stone should be at the center. Click on a stone, then click on adjacent empty space to move that stone to that space. The way that works for me is to move white stones to one end to have space to work in and then move the black stones to the opposite nearly empty side. When correctly done, a grating sound is heard. Just follow the sequence in the images below.