Pick a code for your players
Easy: letter numbers, where A is 1 and Z is 26 (“look under the clock” is 12-15-15-11 21-14-4-5-18 20-8-5 3-12-15-3-11), backwards text and upside-down text. Players can crack them with no key, or a very simple one.
Medium: a Caesar shift, Morse code and braille. They look like gibberish, but a key or a little thinking solves them.
Hard: runes, ogham and binary. They mean nothing until players find the key, so hide the key somewhere else in the room.
Making a good coded clue
Keep the message short: a word, a number or a place, such as “look under the blue chair”. Give players a way in: print the key and hide it as its own find, or hang a Morse code chart or braille alphabet on the wall. Then solve the printed clue yourself, or better, ask someone who hasn’t seen it.
Solving a code
Switch to Solve a code, pick the code, and type or paste what’s on the clue. Morse code, braille, binary, letter numbers, Caesar shifts and backwards text can be read back here. If you don’t know a Caesar shift, show all 25 and look for the one that makes sense. For runes and ogham, use the key printed with the clue, or the rune alphabet and ogham alphabet charts.