Move the circle with the plus sign to the green circle with the check mark. In each level, there are various circles that act as obstacles. The first circles that you will encounter are dark gray ones, which don't move. The game becomes more challenging as purple, orange, yellow and blue circles with arrows are introduced. Circles with arrows will move according to your movements. Circles with minus signs appear later in the game; these appear and disappear when you move vertically. Lastly, there are green circles with O's and red circles with X's, which correspond to each other. Touching a green O circle will make all red X's disappear or reappear.