Choose Your Own Adventure

As a child, I loved the Choose Your Own Adventure series of books. In these books, you (the reader) are confronted with a series of choices, sending you to different plot lines within the book. Some endings were positive, many are negative and even lead to the reader's death. I read these books over and over. At one point or another I owned 20 or so of the series of 184, and I read many others from the school and public library.

As an adult, I thought about using network analysis and graph theory techniques to understand how the series of books evolved over time. Each book can be represented as a directed graph, with each page corresponding to a node. Links represent transitions between pages. Pages that have choices are "diverges," with multiple outgoing links. A traditional book forms a linear graph, each page leading directly to the next. Choose Your Own Adventure books have a more complex structure which I'll explore here.

On starting this project, I've learned that I'm not the only child of the '80s who remembers these books fondly, and has analyzed them in this way. First and foremost I mention Dr. Jeremy Douglass of the University of California, Santa Barbara, whose research involves interactive fiction. I have reused the graphviz templates from his Transverse Reading Gallery, only adding color-coding for the endings, and making a few minor edits, in my analyses below. Some other visualizations and analyses I've found, in no particular order:

1. Visualizations and analysis of several books in the series.
2. A survey of visualizations and many links, assembled by Mark Sample.
3. Visualization and analysis of book 2, Journey Under the Sea by Michael Niggel.
4. Visualization of The Third Planet from Altair by Greg Lord and accompanying essay .
5. Visualization and analysis of book 53, The Case of the Silk King, by Gregory Bratton.
6. Some discussion of the visualizations printed on recent editions in the series, from Sarah Laskow.

I was delighted to find that many of these books are available to borrow on the Internet Archive Library, and have started a project to analyze the structure of all 184 books in the Choose Your Own Adventure Series. This is an ongoing project that I will work on as I have free time, and I estimate it will take at least several years to complete.

For each book, I will do the following:

1. Compute the number of distinct paths through the book. This may not be the same as the number of endings, since an ending is often reachable through multiple paths. Each of these paths is acyclic and does not repeat any page.
2. Determine whether there are any cycles in the book. If so, you can read as long as you like by repeating the choices in the cycle.
3. Discuss the distribution of path lengths in the book. Do readings of the book tend to be short or long?
4. Determine the difficulty of the book. I assign a numeric score to each ending: 5 is the best possible ending; 4 is slightly positive; 3 is neutral; 2 is slightly negative; 1 is very negative (often involving the character's death). On occasion I may apply a 0 score for a catastrophic ending (e.g., not only do you die but you cause the deaths of many others). In a difficult book, the "good" endings hard to find; perhaps few in number, or buried deep in the book and requiring many correct choices to be made. Assuming every choice is made randomly, I compute the expected ending score, and subtract it from 5 to compute the "difficulty" of a book. Lower scores denote easier books, and higher scores more challenging books. To my knowledge, this kind of analysis is novel.
5. Discuss other properties of a random walk on the book.
6. Give an overall rating of each book (1-5), with subratings for narrative, fun, and nostalgia.

I will also highlight any particularly interesting pages, and write a short review of each book. Some of these will reflect differences from what I recall as a child and my experience reading them afresh.

Summary table

Capsule reviews

Full statistics here. The Cave of Time is "the book that started it all"; the premise is that you discover a cave whose branches lead you to different places and times. There is a lot of branching, and most of the paths are fairly short. The graph is nearly a tree, with only two pages that can be reached in multiple ways and no cycles. There's no common narrative connecting the different paths through the book, or even a clear goal for you to achieve; "trying to get home" is the obvious goal, and in some of the paths it's clear you're trying to return to the present, but in many of the other paths you seem perfectly content to live in another time. Reading through the different paths in the book mostly gives the sense of random jumps between different points in time, and relatively short plots. It's entertaining enough to play through a few times, but compared to some of the later books in the series, there's less "replay value" in trying to unravel a mystery or achieving a goal. I have always been a sucker for time travel stories, though. There is one ending where you end up far in the future and watch the sun die out, which is bleak yet poignant; that ending has stuck with me since childhood.

1. Narrative score: 2/5
2. Fun score: 3/5
3. Nostalgia score: 4/5
4. Overall score: 3/5. Clearly an important book in starting things off, but viewed in light of the whole series the structure is basic, the plotting random, and the paths are short, so I can't give it a higher score.

Full statistics here. You are an undersea explorer trying to find Atlantis. Compared to The Cave of Time, Journey Under the Sea is a much more complex narrative, with many paths that diverge and rejoin, two cycles, and a few "key pages" (6 and 9) that serve as reset points in the story. There are some significantly longer paths than in The Cave of Time. The goal of finding Atlantis is interesting, and a common thread that connects most of the paths through the book, but the stories aren't always consistent. Atlantean society is portrayed in contradictory ways (are they descendants of ancient humans, or are they aliens, or is it actually a secret military base?), and confusingly there are some paths that cover several versions of Atlantis in the same read. The longest path in the book is one of them. There are some New Age-y parts of the book, involving metaphysical "thought travel" and the like; in this regard it seems very much a product of 1970s. In all, it's an enjoyable read with some creative storytelling.

1. Narrative score: 4/5
2. Fun score: 3/5
3. Nostalgia score: 4/5
4. Overall score: 4/5. Another important book, this one pioneered a more complex narrative style.

Full statistics here. What a zany book! You and your friends take a ride on a hot air balloon, and a storm takes you towards the Sahara Desert. This is a crazy adventure with many different settings, including salt-hunting aliens, a submarine hunting whalers, secret cities, time warps, treasure hunting, and so forth. I remember this book very fondly from my childhood. Some of the storylines cross; there is one where you encounter yourself in another hot air balloon, and time warps involving a cave with a mysterious set of colored doors. The different settings are connected in many ways, and there are 388 distinct paths through the book (The Cave of Time only had 54!) The book has a lighthearted tone, and a lot of nonstandard endings. None of the stories makes a whole lot of sense, and the endings are often contradictory (is the underground river really an amusement park ride, or not? Will the revolutionaries let you go in peace or not?) but it's great fun to go through.

1. Narrative score: 3/5
2. Fun score: 4/5
3. Nostalgia score: 5/5
4. Overall score: 4/5. This one's really "out there." It's fun, but I hope there aren't too many more books like this.

Full statistics here. This book really doesn't make very much sense. A shame, since I usually like space stories and I actually have a fond memory of this book from childhood -- I discovered my first cycle in this book, and was delighted that I could keep reading over and over and over again if I remembered the right sequence of choices. But unfortunately the story doesn't hold together. It's a random sequence of disconnected space vignettes that have little to do with the specific choices you make; sanctimonious preaching about peace using thinly veiled metaphors for Earth (in fact, at one point there is a continuity error where you are initially on an "Earth-like planet" but a few pages later R. A. Montgomery has given up the pretense and you're just on Earth); and way too much metaphysical woo (you eschew formal education to discover "the knowledge within yourself," which of course includes the ability to time travel by thought... but when you do you suddenly have some time control device with buttons?). I don't know if this is supposed to be some kind of absurdist performance art, but it just isn't a fun read.

1. Narrative score: 1/5
2. Fun score: 1/5
3. Nostalgia score: 2/5, because of how delighted I was to discover a cycle.
4. Overall score: 1/5. I won't be reading this one again.

Full statistics here. I had never read this book as a child -- and man, did I miss out! This book has the most coherent and tightly-written plot of the series to date; all the branches explore the same underlying story from different sides, and as you re-read you get a greater picture of what's actually going on in the house. Edward Packard sets the mood well, with a surprising level of creepiness and horror in a children's book, including a Sisyphean ending where you are cursed to forever piece together a broken china cat, or ghostly eyes staring at you from the darkness. There are some paths that twist and turn, even if the graph isn't as tangled as the last three; the longest path in the book is 27 pages, more than any other thus far, and it moves more-or-less seamlessly among the different plot threads (just a slight "oops" where you realize the cat "must be Melissa" when that name hasn't been mentioned in that path before). This is exactly the kind of story that this narrative format is best suited for.

1. Narrative score: 5/5
2. Fun score: 4/5
3. Overall score: 5/5.

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