The worlds created specifically for the game mirror the overall appearance of the other worlds and feature either new characters or ones from several "Final Fantasy" games. The new worlds include: the Destiny Islands, where the story opens; Traverse Town, which serves as a launching point for most of the game; Hollow Bastion, which many of the "Final Fantasy" characters call home; and the End of the World, a large, dark world created from the remnants of various worlds consumed by the Heartless. The main characters travel from world to world to seal each "Keyhole"; this protects the world from the Heartless and ultimately from destruction. They also try to minimize their interaction with characters of other worlds to maintain a balance of separation. This sometimes requires Sora, Donald and Goofy to blend in with the world inhabitants by changing their physical appearance.