The game is played with touch controls on a 7x7 square grid. In each round, the player places a disc that falls from the top of the grid. Each disc has a number 1-7, or a blank. Whenever the number of any disc matches the number of contiguous discs in a row or column, that disc disappears and also hits any blank discs it touches. When a blank is hit twice, it turns into a numbered disc. The round ends and a full row of blank discs emerges from the bottom of the grid. (wikipedia.org).