Draw to make cuts that allow to activate the mechanism and so the ball reaches the exit portal. Have in mind that there's areas that cannot be cut. In certain cases you'll have to catch the gravity bonuses, that invert gravity in a level, or cut certain ropes. The game allows you to select between 2 ways to reach the end, one through the easy levels (the blue way) and the other through the difficult ones (the red way). And a comprehensive level editor.
Click, drag and release to cut from one point to another.