"The concept for this game is as idiosyncratic as its predecessor. Since the release of the original game, the King of All Cosmos and his son the Prince have acquired a fan base. The Prince receives a request from a fan at the start of the game. The objective of the game is to have the Prince fulfill each fan’s request, which will make more fans (stages) appear until the whole game is mobbed with fans. Upon fulfilling each fan’s request, the Katamari is given to the king, which he uses to create a new planet in the cosmos, this continues until there are enough planets in the cosmos to roll up the sun using the Earth as a katamari. Constellation data can be loaded from Katamari Damacy to help with this task.
The gameplay follows the same core mechanic: To gather material, the Prince pushes around his katamari, a magical, highly adhesive ball capable of grabbing anything smaller than itself. Initially, the katamari can only pick up smaller items like loose change and discarded pencils. As more items accumulate, the katamari’s power grows, allowing it to pick up “vaulting boxes, pencils, erasers, postcards, ramen, robots, cows, sheep, this girl, that boy, moms and dads, bicycles, motorbikes, homes, buildings, rainbows, clouds, islands, hopes and dreams”. Once the level is successfully completed, the katamari is launched into space and becomes a planet, satellite, or other celestial object. If the planet has already been created, the katamari can replace it or be shattered into “stardust”."
Source: Wikipedia, "We_Love_Katamari," available under the CC-BY-SA License.