YU-NO: A Girl Who Chants Love at the Bound of this World is a Japanese visual novel / graphic adventure game developed originally as an adult game. The game’s protagonist travels between various parallel worlds in order to solve the mystery of his parents’ disappearance. Although parallel worlds are not an unfamiliar concept in science fiction, the game uses concepts from physics, mathematics, philosophy, history and religion to construct a unique fictional universe. In particular, the “A.D.M.S.” or “Auto Diverge Mapping System,” which visually displays the branching parallel worlds/storylines as a tree, aids the player in navigation. The game also includes references to cannibalism and incest. All versions are rated 18+, although explicit sex scenes were removed from the Saturn and Windows editions.