So far, we have discovered how to use the pair and star touch-scheme to fill the board. But not all levels can be won this way. How to handle remaining tiles ?
The answer is to move those tiles together, so that they either disappear or form some known form.
In this animated image, you can see how diamond-shape groups of tiles move. Between each snapshot, only one tile was touched : the one closer to the new position of the diamond. Beware that diamond only move toward the direction pointed by one the two largest angle. As usual, you can see that the same methods apply to the side of the board (you only have to find a triangle, in place of a diamond).
Of course, touching back the same tiles will move the diamond (or triangle) back to its starting position. Please not that hitting a wall with a moving diamond results in a two tiles group, because we will be using those in the next article !