You have to draw cards one at a time from your stockpile. Select the cards that are one higher or one lower in value to your drawn card to remove it from the playing field. To complete a level you need to remove all the cards from the playing field without running out of cards from your stockpile. Cards are available according to mahjong rules. That is, if there are no cards on top and at the same time on the right and on the left, then the card is available