The use of branching narratives in literature dates back at least as far as 1941, with Jorge Luis Borges' Examen de la obra de Herbert Quain which describes a story that branches to multiple endings. These early works and similar, later, works of literature are not considering "game" enough to be listed on RPG Geek.
The introduction of RPG-like game elements to these types of book was pioneered by the Fighting Fantasy series which added character attributes, randomised task resolution, and item inventories.
But various titles of gamebooks that do not have any RPG-like system are still listed on RPG Geek (due to their historical importance, their links to RPG franchises, or their marketed appeal as a game). This entry links together these separate series of books which each have their own individual listing in the database.