Alternate Timelines

Variations of the Official King's Quest Timeline
King's Quest originally had one timeline, the official timeline that covered events of all the games. Later novels and the companion were added to it.

Each of the sources never specified any specific dates for when the stories took place, though the manuals implied how much time passed between each game. Even the official timeline had two different theories on the existence of Daventry placing it in two different points in time or place. The manuals and KQ6 intro movie implied that the games occured a long time ago in earth's past, for example, but the companion implied that people withdrew from earth a long time ago to daventry, and now Derek Karlvaegen is sending history of his world to earth.

With the release of King's Quest I (remake), an additional alternate version of the King's Quest 1 storyline was made, which included more dialogue, and altered a few details in the game, puzzle solutions, and forced the order in which the 3 treasures of Daventry could be found into a specific order ending with the Magic Shield. One altered detail in the storyline for example was that serpent-like moat monsters had replaced the alligators that existed in earlier versions of the game. Though these changes were relatively minor, and the two games storylines remained relatively the same.

Additionally there was an official version of King's Quest 1 made for SMS, and an official version of KQ5 made for the NES, both had a few minor alterations from their respective games. The SMS King's Quest had new art for the people and places of Daventry, and interface similar to early Lucasarts adventure games, a few of the puzzles were altered in order to work with the interface, though the text of the story remained largely the same. KQ5 for the nes, had an interface similar PC disk version but the art design for the various locations was much different, and some places like the desert were reduced in size. Some of the dialogue was modified, location names changed, some of the cut scenes removed or shortened (for example Amanda and Austin never show up), and certain puzzles modified or changed. For example dink will come from anywhere in the maze from the sound of the tamborine rather than than graham having to find him in one of his 4 rooms, and the maze is different than in the pc version. Additionally the sea monster at the edge of the sea is a tentacle rather than a loch ness type monster. However both adaptations stayed true to the original storylines.

King's Quest Companion chose to follow the original version of the story (rather than rewrite the novelization to incorporate the new material) as it was the most common version of the game released at least up to the 3rd edition of the book, and it would go against the conceit behind the story(refrences to the conceit were removed in the 4th edition due to the remake being more common than the original version by then), where as the official novels refrenced directly from the remake (serpents in the moat rather than alligators). However the differences were minor at best, this was kept up through the 3rd edition. However it somewhat branched from the game's timelines in the 4th edition by implying that KQ7 was a fictional story within the King's Quest universe that contained more lies than truth. Though Derek admitted he didn't know for sure, and that the royal family may have chosen to keep the true events secret from him, or that some kind of great dreamer in his world was altering the face and history of his world.

In this timeline it is implied according to the King's Quest Companion that Rosella and Edgar would utimately become the Heirs of Daventry implying a happy ending to the series as a whole.

Fan Timelines
With the release of more and more fan made games even more alternate timelines have arisen.

KQ2 (AGDI) Timeline;
The first alternate timeline arose with the existance KQ2 (AGDI) which altered many characters turning several who were once villains into allies of King Graham, and other characters who were once good or neutral into Graham's enemies, it removed a few characters from the story, added new characters, and changed the face of Kolyma, Neptune's Kingdom, and even the existance of the Enchanted Island (turning it into a snowglobe in Hagatha's cave). Although consistent to prequel and sequel games of the series, it's inconsistent to the Companion which followed the original version of the adventure. This formed the KQ2 (AGDI) Timeline and which has specific dates, as well as dates that could be interpreted from the given dates on tomb stones. It set its own storyline over the course of three days in Kolyma.

In this continuity King Graham was cursed so that none of his blood heirs would ever receive the throne of Daventry, taking the universe in a much darker and somber direction. Connor becomes the heir of Daventry instead.

KQ3 (IA) Timeline;
While the unofficial King's Quest 3 remake by Infamous Adventures is likely intended to be set at the same time as original King's Quest 3, the ending differs from the official timeline. In the official timeline only about an hour had passed between the ending of King's Quest III and King's Quest 4, from the time of the initial reunion to Graham's heart attack.

However in unofficial KQ3 remake's chronology, several months passed between the initial reunion and King Graham's decision to pass on his Adventure's cap, in which Alexander and Graham got to know each other, as they worked on the repairs of the kingdom.

The Silver Lining Timeline;
Another unofficial timeline was the one created for The Silver Lining that places specific dates on events but is said to ignore the events of KQ2 (AGDI), to instead follow the official continuity.

However the dates it locked down for certain events are not necessarily consistent with the points in time implied by official material.

King's Quest ZZT Timeline;
In the ZZT series, its timeline is based off the titles of the games, and the world is known as "King's Quest".

For example Alexander refers to the era of King's Quest 3 by saying;

"Hey, its the evil sorcerer Manannan who I turned into a cat in King's Quest 3".

Basically each of the alternate timelines can be considered as existing in alternate universes that mirrored the original timeline with some unique differences.