The series began in 1992 with the release of the book simply titled I Spy, which did not have much of a unifying theme; later on came a multitude of other books, though, such as I Spy School Days which has a classroom theme and I Spy Spooky Night which takes place inside a haunted mansion. It quickly became a huge success and spawned a whole slew of spinoffs aimed at various age groups and even a series of (surprisingly well-made) Licensed Games for various game consoles, but most often the PC. Although main series books are a lot less common nowadays, all of the older books are still in print and still easy to run across in the children's section of your local bookstore, and don't be surprised if you're still running across them in the average elementary school classroom.
It was also adapted into a stop-motion animated series, which aired on HBO Family between 2003 and 2004 for 26 episodes. This show was in a somewhat different format, being an edutainment series, but hidden, random objects still remained a core part (even the main characters are made up of random objects).
Not to be confused with the spy show of the same name, or the UK "I-Spy" books, which were a series of books about things to look out for in the world around you, along the lines of the Spotter's Guides.
The books in the I Spy series provide examples of the following tropes:
- All Just a Dream: I Spy Spooky Night ends with the implication that it was a dream a child had about their dollhouse before Halloween.
- Christmas Episode: I Spy Christmas
- Circus Episode: I Spy Fun House
- Extended Gameplay: Extra Credit Riddles, which were introduced in Mystery, are sets of extra riddles for each picture. Also, the "Find Me" riddle, which tasks the reader to find a single object that appears across every picture in the book, and the Challenger books (which include new, harder riddles for previously released photos).
- Guide Dang It!: Some of the objects are hidden in pretty mean places. This gets even more true in the "Challenger" books.
- Haunted House: I Spy Spooky Night. I Spy Mystery also features a glimpse into one in the "Ghost in the Attic" spread.
- Rube Goldberg Device: "Levers, Ramps, and Pulleys" in School Days. The machine actually worked too!
- Scenery Porn: For a series of books aimed at kids, the pictures have some very impressive and stunning looking sets. Being blown up to massive size and really being able to see all the details definitely helps in that regard.
- Something Completely Different: I Spy Treasure Hunt has a more linear storyline (with an almost First-Person Shooter-style perspective to the photos) than the other books, and the photos are mostly of model environments (a seaside village, an island, a cave) built with ordinary O-scale props, with hidden objects mixed in instead of a jumble of items arranged around a theme. It also features some specially-drawn traditional art in the form of the treasure map the story revolves around.
- Treasure Hunt Episode: I Spy Treasure Hunt, natch.