Game books are books that, in addition to being read, are played like a game. This can include books with branching plot lines, book with special game rules, activity books, mystery books, and hidden picture books. Most game books are designed to be solitary endeavors for a single reader. Game books date back to the 1930s and peaked in America in the early 1980s. They saw a serious decline with the growing video game market, but they are still being published to this day.
I really liked game books as a child, but I don't care much for them these days because I think that they can pretty much always be made considerably better as video games. However, I still appreciate them as a historical medium. I still think about creating a game book every now and then, and have even started several times, but I can't maintain the motivation to keep it up. I discuss the strengths and weaknesses of game books in the sub-sections below.
Game Book Types
Branching Plot Books
Branching plot books are stories where the reader is allowed to choose, from a limited number of options, how the plot will progress. Books like this include Choose Your Own Adventure and Find Your Fate. I owned several of these growing up and read about a dozen more from my school's library. While I liked them as a child, I became disenfranchised with them by my teens. They tend to be targeted toward children and young adults so the stories aren't that great, your decisions usually don't affect the story, and the books rarely try to present a coherent story line. Instead, each branch takes the reader down a path that alters the reality of the fictional world. For example, in one branch, your teacher is a space alien in disguise, but in another, they're just a normal human. I prefer those stories where you can make various decisions based around a plot line, but the plot itself is fixed.
Books With Game Rules
These books usually feature branching plots, but also use rules more commonly found in pen-and-paper role-playing games to add elements of skill and randomness to the story. Examples include the Lone Wolf Series and Fighting Fantasy. I prefer these books to the traditional branching plot books and continued to like them well into my teens. However, by adding elements of randomness, you may often find yourself killed due to a bad roll of the dice and having to start the book over from the beginning, which is quite dull.
These include books with assorted games and activities in them like crossword puzzles, cryptograms, cutouts, and more; stuff I really loved in elementary school. In general, they're pointless busy work, but occasionally you will find an activity book that goes well beyond the traditional games, like the Where's Waldo: Ultimate Fun Book. I've always wanted to make a very complex adult activity book, but have never really figured out how I would do it.
Mystery books are those whose stories include clues that allow clever readers to figure out what really happened in the story. Examples include Two-Minute Mysteries and Encyclopedia Brown. In general, I don't care for these books because each mystery can usually only be solved if the reader knows some esoteric fact. However, after failing and reading the answer, you do gain some new insight for the future.
Hidden Picture Books
These are books with collections of drawings in which pictures are hidden in them. Popular titles include Where's Waldo, For Eagle Eyes Only, and compilations of the Hidden Picture games from Highlights magazine. I still enjoy these today when the art is complex and interesting.