"The Endless Quest books were two series of gamebooks released by TSR. These books were the result of an Educational department established by TSR to develop curriculum programs for reading, math, history, and problem solving. The first series of 36 books was released from 1982 to 1987, the second series of 13 from 1994 to 1996. These were respectively the first and last gamebooks released by TSR. A short spin-off series of 4 Endless Quest: Crimson Crystal Adventures books were also released during 1985. There were also several series of similar books that did not bear the Endless Quest name.
The mechanics of these books involved simple choices in the style of Choose Your Own Adventure books, rather than the game-like randomized elements of Fighting Fantasy gamebooks. However, the stories and characters in an Endless Quest book, while not necessarily more complex than in a Choose Your Own Adventure book, are often more fully developed because the Endless Quest books are much longer. For example, the character referred to as "you" in the text almost always has a name, gender, and backstory. The result is that the books in the Endless Quest series resemble miniature novels with many different endings.
The majority of the books in the series were based on Dungeons & Dragons, but some were based on other TSR games (e.g. Gamma World, Top Secret) or even licensed properties (e.g. Conan, Tarzan)
Mirrorstone, a division of Wizards of the Coast that publishes fantasy fiction for children and teens, began republishing the Endless Quest series in January 2008. The first book in the series is a revision of Claw of the Dragon (#34 from Series One) They have updated the book including making it gender neutral so it can be enjoyed by both boys and girls, and plan to update and publish more of the D&D books pending the success of this first title."
Source: Wikipedia, "Endless Quest", available under the CC-BY-SA License.