Aimed at younger readers, these books were published in paperback form only, with brightly coloured covers and were heavily illustrated in black and white throughout. Unlike other series of interactive novels such as Choose Your Own Adventure stories or Fighting Fantasy gamebooks, each Interplanetary Spy book is made up largely of illustrations in a style that mixes comic book-like line drawings with blocky, straight edge illustrations matching the graphical quality of video games from the time of publication. Rather than requiring readers to select from various actions and directions, or succeed in dice driven 'combat' to progress through the story, these novels mostly involve puzzle solving. Image-based challenges such as mazes, pattern matching and visualization problems are common throughout the series, with all stories being presented in second-person point of view.
