RuneQuest quickly established itself as the second most popular fantasy role-playing game, after Dungeons & Dragons. The first and second editions were set in the mythical world of Glorantha, while the 3rd edition in the mid 1980s was more generic and much less successful.
The game had been sold to Avalon Hill under a complex agreement that required all Glorantha-related content be first approved by Chaosium. In an attempt to also have a setting they could release freely, Avalon Hill also supported a new "default" setting, Fantasy Earth, based on fantasy interpretations of several eras of earth's pre-modern history.
While some of the supplements for Fantasy Earth were well-written, the popularity of RuneQuest as a system seems to have come from the strength of its original setting, which was reflected in remarkably high sales of materials that were new editions of out-of-print Glorantha content. A proposed 4th edition was originally meant to return the tight RuneQuest/Glorantha relationshup, but it was shelved in mid-project.
Glorantha is now served by a new rules system called Hero Wars. Part of the agreement that permitted a new Glorantha-based game was that Avalon Hill retained rights to the name "RuneQuest" but not to the RuneQuest game rules. An attempt was made to produce a new game called "RuneQuest:Slayers", that was neither Gloranthan nor used the original rules but it, too, was shelved.
The rules system developed in RuneQuest was widely reused by Chaosium and it is called the Basic Role-Playing System (BRP). It forms the basis of several of their other games including Call of Cthulhu, Stormbringer and Corum.
Steve Perrin, one of the authors of the original RuneQuest game, later developed a similar system known as SPQR_RPG (Steve Perrin's Quest Rules), which some RuneQuest fans consider to be a successor to the original game.