In each level, you have to click on a token and then on a blue circle in any direction. The token will move in the corresponding direction, but only if there's another token in the way. That token will be beaten and the other token will move behind it. However, later you discover white tokens, which beat and can be beaten only diagonally, and gray tokens, which can move even if there aren't any tokens in the way. If you end a level on a star, you collect it. You need them to unlock chapters.