KQIX, the unofficial ninth sequel to the King's Quest series was recently shut down after developers received a demand letter from Vivendi Universal Inc.
The legality of unofficial sequels is sometimes uncertain. It often depends on the extent to which intellectual property from the original game is included in the sequel.
For example, if the sequel uses trade-marks from the original game such as the name of the game (or sometimes even the names of characters or places in the game), the sequel might violate trade-mark rights in the original game.
Likewise, if the sequel uses any code, characters, or other materials from the original game, the sequel might violate copyright in the original game.
Shut down site is at http://www.kqix.com