Pong is a simple game that most can understand. It behaves similarly to a game of table tennis, and has had numerous iterations over the years. In its simplest form, the ball moves with constant velocity between two paddles until one misses it. In real life, the ball would have to exist on a frictionless surface and face purely elastic collisions with both paddles in order to retain a constant velocity without any forces acting on it. The closest we can come to this is air hockey, and even then the puck eventually slows down and does not retain velocity upon collision.