In the game, you play as a small human-like being, who is a prince. His father is the king of the cosmos. In the beginning, the king destroys all of the stars in the galaxy without meaning to do so. He then asks his son to take a magic ball (the Katamari). The king then sends the prince to Earth. The ball can make things stick to it. The point of the game is to roll enough things onto the ball. Once this limit is reached, the Katamari is sent to the king for evaluation. If it is big enough, the ball will float into the air and turn into a star.