Kingdom Hearts: Re:Chain of Memories picks up right after the events of the first game, set within Castle Oblivion, a mysterious fortress kept by Lord Marluxia. Sora and his companions are warned that the castle strips its visitors of their memories the moment they enter. The lobby and the spaces between floors are white and decorated with floral motifs, but each floor can be reshaped into a world from the first Kingdom Hearts using "world cards" formed out of Sora's memories. As before, many worlds from Disney and Square Enix make a return.
Unlike the original, however, these worlds are spun from Sora's memories, so many of the events he lived through in Kingdom Hearts play out again here, with Sora meeting memory-based versions of Disney characters he's encountered before. The individual storylines diverge from those of the first game and orbit the theme of memory. Just as Kingdom Hearts featured worlds built specifically for it, Re:Chain of Memories introduces Twilight Town — a world drawn from memories on "the other side of [Sora's] heart" — in addition to the returning worlds.