Making a puzzle, treasure hunt or escape room

A classroom code-breaking lesson, a birthday treasure hunt, an escape room at home or a puzzle geocache all need clues that can be solved, lead to one answer, and can be printed or played. These tools build and check them. For the solver’s side, see Solving an unknown cipher and Solving a geocache puzzle.

1. Start from the answer

Decide what opens the last lock first: a word, a four-digit code, a place. Then work backwards, with each clue giving the next clue or part of the answer. Letters become numbers with A = 1, B = 2 and so on, which turns a word into a padlock code.

2. Make sure each clue has only one answer

The most common fault in a home-made puzzle is a clue with two good answers.

• A scrambled word: put the letters into Anagram Solver. If they also make other words, players may stop at the wrong one: listen is also silent, enlist, inlets and tinsel. Choose a word whose letters make nothing else, or add a hint.
• A fill-in clue such as a word with only some letters showing: type it into Crossword Helper with a ? for each hidden letter. ?a??le fits 51 words, from babble to wattle; show more letters until only yours is left.

3. Encode the clues

Choose a code that suits the players and the room:

• On paper or a wall: Picture Alphabets writes pigpen, semaphore flags, maritime signal flags, Braille, runes and Greek letters. Download SVG prints sharply at any size, and the decoding key is easy to hide somewhere else in the room.
• As a sound: Morse Code plays the message and Download WAV saves it, for a phone or speaker hidden in the room. Slow the speed down for beginners.
• A keyword cipher: Classical Ciphers has Vigenère, Playfair, Atbash, Rail Fence and twenty more. The keyword becomes another clue to find.
• A wartime theme: Enigma Machine encrypts with the real machine’s settings. Hand the settings out as a codebook prop; typing the message with the same settings decrypts it.

Keep a copy of every clue with its answer: it’s easy to forget how one was made.

4. Make a reveal

Visual Cryptography splits a word or picture into two images of random dots. Each alone shows nothing; laid on top of each other, the secret appears. Download both shares and print them on overhead transparency film at exactly the same size, then hide them in different places. A larger Pixel size makes them easier to line up by hand. The secret shows as black on grey, so use big, bold text.

5. Playtest it

Solve every clue yourself from what the players will have, not from your notes. Then try the encoded messages in Solving an unknown cipher: if the cipher identifier and cracker solve it at once, the puzzle is easy for anyone with a phone, which may be fine for children but not for a room of adults. Finally, give it to someone who hasn’t seen it, and watch where they get stuck.