Every letter becomes a pair of digits, thanks to a simple 5x5 grid.
Turn this message into a real game: create a virtual lock your players must crack open.
The Polybius square arranges all 26 letters into a 5-by-5 grid (I and J share one cell). Each letter then becomes two digits: its row number, followed by its column number — for example, "31" for the letter L. Simple to build, simple to read back.
This system dates back to ancient Greece, where the historian Polybius described it as a way to send messages across long distances using torches — raising a number of flames for the row, then the column. A true ancestor of Morse code, over 2,000 years before electricity.
For an escape room, the Polybius grid works wonders: it turns a simple table into a game object in its own right, something players have to physically find in the room before they can even start decoding the hidden message.
Plain message
LOOK UNDER THE ROCK
Coded message
31 34 34 25 / 45 33 14 15 42 / 44 23 15 / 42 34 13 25
Because a 5x5 grid only has 25 cells for 26 letters. I and J, both fairly rare and easy to guess from context, get merged into one cell without really slowing down decoding in practice.
The first digit gives the row, the second gives the column. For "31," you go to row 3, column 1 of the grid and read off the letter there. With a printed grid in hand, it's practically instant.
Yes — on CrackAndReveal you create a lock whose expected answer is the word decoded from the grid. Players work out each letter, type their answer online, and the lock opens automatically, with no manual checking needed from you.
Yes, its coordinate-based idea directly inspired later ciphers like ADFGVX, used by the German army in 1918 to encrypt front-line messages — proof that this ancient Greek trick was still remarkably effective more than two thousand years later.
With CrackAndReveal, your coded message becomes a virtual lock to crack: players decipher your code, enter the solution and reveal your surprise.
Create a free lock