Use your mouse to swap adjacent tiles to create sets of three or more. Collect bomb and pickaxes by moving them to the bottom of the field. After they have been added to your inventory you can use them to make room. Simply press the corresponding button on the control panel and then click on the tile you wish to remove. Rocks cannot be swapped - they can only be destroyed. Watch out for pulsating items: if you don't remove them fast enough they will turn into rocks.