make groups of 3 or more identical elements of the same colour. Easy, may be...
Play with the elements: Put on the board in an empty block or in a block of the same colour (also empty) the active element in the pickaxe. When the arrows are aligned in the good direction, a bonus is added to the score. And when you put an arrow on the board, the empty blocks in the direction of the arrow take the colour of the arrow.