YU-NO: A Girl Who Chants Love at the Bound of this World is a point and click adventure / visual novel game released in 1996, developed and published by ELF for the PC-98. It was written and produced by Hiroyuki Kanno, while its FM-synth chiptune music soundtrack was composed by Ryu Umemoto; they had previously worked on C's Ware titles such as Eve Burst Error (1995), and both Kanno and Umemoto later died in 2011 at the age of 37.
YU-NO was also ported to the Sega Saturn in 1997 and to Microsoft Windows as part of the Elf Classics collection in 2000. The game was later adapted into an anime OVA (Original Video Animation) as well as a manga and several novels.
The gameplay uses a point-and-click interface to interact with the game world, in contrast to most other visual novels which rely more on text commands. The plot revolves around the protagonist time-traveling 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 or timelines as a tree, aids the player in navigation. The game also includes controversial references to themes such as cannibalism and incest.
The game was an important milestone for visual novel and adventure games in Japan, setting the standard that subsequent visual novels would follow. The way Kanno presented the plot, encouraging players to complete different branching storylines and view all the multiple endings in order to gain a better understanding of the overarching narrative, was influential, particularly the way in which all the branching plot-lines are presented as alternate timelines. The original musical score composed by Umemoto was also influential on the musical style used by subsequent games in the genre.
Among visual novels better known in the West, the game's influence can be seen in Key's games (such as Kanon, Air, and Clannad, all of which were adapted into popular anime), titles such as Fate/stay night and Steins;Gate (both also adapted into popular anime), and the Zero Escape series, for example.
The A.D.M.S. system representing different timelines has also influenced subsequent adventure games as well as popular RPGs ranging from Radiant Historia to Tactics Ogre: Let Us Cling Together and Final Fantasy XIII-2. The gameplay element of requiring players to travel through time-space to solve puzzles was also original, with its influence evident in subsequent time-travel adventure games such as Shadow of Memories, Time Hollow, and Steins;Gate.
YU-NO contains one of the largest video game scripts ever written with almost 100,000 lines of dialogue and over four million characters of Japanese text. An ambitious English fan translation for the PC version of YU-NO was completed by a team from TLWiki on September 29, 2011. The translated script uses over a million words of English text. The translation team also added several enhancements to the PC port, including the voice acting and extra scenarios from the Saturn release as well as the uncensored content from the original PC-98 version.