Edward Packard's Choose Your Own Adventure book series was a heady mix of genre conventions, RPG identity-swapping, and dying for no apparent reason. These novels weren't high art, but their innovative structure has prompted analysis decades later.
Over at The Comics Journal, Sean Michael Robinson discusses the transformative aspects of CYOA novels. Despite their wacky high concept plots ("you become a shark," "you encounter a space vampire," etc.) and the assumption that the reader is portraying himself, Robinson found that the books taught him to identify with the fictional protagonists and to divine their motivations:
For Packard the formula wasn't just the concept of branching path fiction– it was also the emphasis on you, the reader, the traditionally robust role of protagonist making way for the ego of the audience to fill in the gaps. This intention was often undercut by the Bantam illustration concept, which more often than not represented the protagonist as a ten-to-fifteen-year-old white boy. In rare instances this tendency was reversed , such as many of the female-protagonist (or even gender-unidentifiable) fantasy-themed books [...]
I disagree with Packard as to the importance of the empty vessel– I don't really believe such a thing is possible, even without illustrations. If the author is doing her job creating an environment and situation for you to explore, a natural result will be a character, even if it's a character created solely by inference. Additionally, even as a younger reader I was very aware of which "characters" I liked and identified with, and how this changed my interaction with the book. I remember as a young boy finding the stories in which "you" were represented as a female strangely compelling, and finding myself drawn to the images of the female protagonists, studying them, trying to read their intentions and motives.
In addition to analyzing the narrative quirks and oddly profound metaphysics of CYOA novels, Robinson also includes a gallery of death scenes and pages from a hilarious CYOA novel he wrote as a child, "Math Escapes." For a crazed quantitative breakdown of CYOA books, check out Christian Swinehart's insanely detailed infographics. The designer has broken down the metafictional possibilities of CYOA books. Swineheart also notes one of the cleverest Easter eggs of the CYOA series: the discovery of the Planet Ultima in the book Inside UFO 54-40, which could only be discovered by cheating and looking through random pages:
In the story, your concord flight is interrupted when you are beamed aboard a nearby spacecraft trolling the universe for intelligent life. Once aboard you discover your new captors, the U-TY, are interested in keeping you around only to the extent that you can help them find Ultima, the ‘planet of paradise'. The planet's location is cloaked in mystery and you are only told that it's a place that cannot be reached ‘by making a choice or following directions'. However this is all foreshadowing for when the reader finally becomes frustrated in the apparently impossible quest and begins flipping through the book hunting for that ending. In fact not choosing is the only way to reach Ultima. [...]
This ending was not just an easter egg for the obsessive reader who didn't mind skimming every page looking for telltale words. Instead it's hard to miss in even a casual riffling. A two-page illustration showing what could only be paradise (or perhaps a theme park) leaps out as the only spread in the book without any text. Flipping to the page before brings you to 101, where you discover that your curiosity has been rewarded. You have found the planet, not by following the constraints of the system, but by going outside of them – a fitting moral to the story and an encouraging reminder that any game should be a starting point for the imagination, not the end.
And for those of you who can't get enough of CYOA, here's a massive database of the books (with their killer covers too, natch).