Each game of pinball has its own set of tasks or "rules" that a skilled player will try to complete during the course of a game. One thing that is common to any pinball game is to keep the ball in play. From the time the ball is launched into the playfield until it "drains" there are a number of objects that will come into contact with the ball. In addition to the gravitational force which always acts on the ball each of these contacts with playfield objects will have an effect, however large or small, on the ball.