Prince Alexander is tormented by his desire to see princess Cassima of the Land of the Green Isles again, whom he shortly met at the end of King's Quest V, when king Graham of Daventry rescued his family and Cassima from the evil wizard Mordack. Unfortunately Alexander could not find any information about the Land of the Green Isles or Cassima since they first met. One day the magic mirror reveals her image, and Alexander, guided by the stars, sets sail to her far-away land. Upon arrival, the ship crashes into the rocks and Alexander arrives at shore, alone with no more possessions.
It appears that during her capture by Mordack, Cassima's parents had passed away and that the vizier, assisted by his powerful genie, has taken control over the land. Alexander is not allowed to see Cassima as she is mourning over the loss of her parents and is soon to be wed to the vizier. In addition the land, which consists of multiple strange islands with each their own inhabitants, is at brink of a war, as they accuse each other of having stolen their most prized possessions and, since the only ferry is no longer functional, they cannot communicate to solve their issues amicably. For Alexander, these circumstances are all too strange to be coincidental, and he begins to travel the islands, using a magic map, meet its inhabitants and reveal the true intentions of the vizier. Question is whether he can gather enough evidence to unmask the vizier before he weds princess Cassima, becomes king and gains total control of the land.
King's Quest VI was written and designed by Roberta Williams, who designed all previous King's Quest games, and Jane Jensen, who would design her own game series shortly after this project: the infamous Gabriel Knight series. As a result of the collaboration between these two magnificent game designers, King's Quest VI is by many fans considered as the high-point of the King's Quest series. It was also the last King's Quest game to be released on floppy disks. The multimedia CD-ROM release features voice acting by professional actors. Another landmark of this King's Quest game is the 3D graphic introduction sequence, created by Kronos Digital Entertainment. King's Quest VI also contains multiple endings and two paths to completion: the long path involves visiting the land of the dead to find the grieving spirits of the parents of Cassima and return them home, as well as restoring the peace between the islands.
Designed with Sierra's SCI engine and featuring VGA graphics, King's Quest VI was initially released for MS-DOS in 1992, on a staggering twelve floppy disks with dialogue and narration presented in text only (with the exception of the intro sequence, which was fully voiced). In 1993, an MPC version on CD-ROM was released for Windows and MS-DOS. The Windows version contained higher-resolution character portraits seen when a character was speaking. This version also featured full voice-acting and a retouched interface (the icon bar and items were increased in detail and the text boxes were re-colored from yellow to brown). The game was also ported to the Commodore Amiga (released 1994) and Apple Macintosh.
The game's soundtrack was composed by Chris Braymen, with exception of the "Girl in the Tower" track which is based on King's Quest V's "Cassima's Theme", composed by Mark Seibert. This track was added to some of the releases as an audio CD and played on radio stations.