Format

After an introduction to the story, the reader is asked to determine the protagonist's next course of action. For instance, the first decision offered in The Cave of Time is:

After the reader makes a choice, the plot branches out and unfolds, leading to more decisions and eventually multiple possible endings.

The types of endings that the books featured include:

• At least one, but often several, endings depicting a highly desired resolution, often involving uncovering a handsome monetary reward.
• Endings that result in the death of the protagonist, companions of the main character or both, or other very negative endings, because of a fatal choice of the reader.
• Other endings that may be either satisfactory (but not the most desired ending) or unsatisfactory (but not totally bad).
• Occasionally a particular set of choices will throw the reader into a loop where they repeatedly reach the same page (often with a reference to the situation being familiar). At this point the reader's only option is to restart the adventure.
• One book, Inside UFO 54-40, revolved around the search for a paradise that no one can actively reach; one of the pages in the book describes the player finding the paradise and living happily ever after, although none of the choices in the book led to that page. The ending could only be found by disregarding the rules and going through the book at random. Upon finding the ending, the reader is congratulated for realizing how to find paradise.

Early books occasionally allowed the player to decide things about the universe, such as whether the unknown person knocking at the door would be funny or scary, but later books only allowed the player to choose his or her own actions.