The Black Cauldron game for the Apple II GS was first video game based on Prydain. It was developed at Sierra On-Line based on the 1985 Disney movie, and was released in 1986. The game was notable at the time for having introduced some unique features, including alternate endings dependent upon how you proceed through the game. The game was designed by Elaine Boulay, Nancy Casolaro, Melissa Haldeman, Al Lowe and Roberta Williams, with graphics by Mark Crowe, at Sierra On-Line in 1985. It was made shortly after the first King's Quest game, so it resembled that adventure in many ways. Along with The Dark Crystal it remains one of only a few adventure games by Sierra to be based on films.