The goal of the game is to make the trajectory of the sputnik as long as possible using the gravity of the planets. Drag several planets from the top left-hand corner to the field. Then press 'start' to launch the sputniks. The red planets pull the sputniks and the blue ones repel them. You may change the mass of a planet by clicking on it. The trajectory is considered to be finished when the sputnik has fallen onto the planet.