Alphabetic Substitution

A very simple way to make a cipher is to create a table that substitutes each letter with another letter. The table is simple. Make two rows of letters: the first row with the letters in order and the second row with the letters in a different order.

One common way of creating such a table is to simply rotate the letters for the second row. (This specific type of alphabetic substitution is known as Caesar cipher.) Here is an example of rotating by 5 letters.

When creating the encrypted text, look up each letter in the bottom row and replace it with the letter in the top row. You end up with text like this:

Now, when players find this message and the cipher table, they can do the reverse lookup and reveal the clear text.

You can choose any character mapping you like. For simplicity, you might try the ROT13 system, which has the letters rotated 13 places.

The convenience of the ROT13 cipher is that the table works both ways. Letter “A” transforms to “N” and letter “N” transforms back to “A”. Likewise, “B” transforms to “O” and vice versa, and so on. This property makes it less likely to make a mistake when encoding or decoding.

Another cipher with the same property can be formed by reversing the order of the letters.

You can, of course, randomize the letters in any order that you wish. But unless you think the players will guess the common cipher, that is likely more trouble than it is worth.

One final note. Simple alphabetic substitution ciphers are known to be breakable without the cipher table. In fact, newspapers often feature “Cryptogram” puzzles that challenge readers to decode a quote encoded with a random alphabetic substitution cipher. However, that should not be a problem as it will likely be easier and more fun for players to solve by finding the decoding table and using that. (If you are really worried about it, make sure players find the decoding table first.)

On the other hand, you could force players to break the substitution cipher without a table. But, frankly, this does not make for a good escape room puzzle. Solving a cryptogram is time consuming and very difficult if you do not have much experience with them. If you are into cryptograms, it is a lot easier to get your fix with a puzzle book than to design a whole escape room.

Symbol Substitution

The alphabetic substitution cipher replaces one letter for another letter. But who says that the encrypted message has to use the same letters or numbers as the plain text message? You can use completely different symbols for the encoded message: hieroglyphics, Braille, emojis, constellations, or anything else you can think of.

A symbol substitution works the as alphatbetic subtitution, just with symbols. Here is a simple cipher example using symbols based on zodiac signs.

A message is a sequence of these symbols. It may contain punctuation (as long as it will not be mistaken for symbols).

And the decoding happens by finding each symbol in the table and replacing it with the associated letter.

One of the nice things about using a symbol substitution cipher is that the symbols can be unique and be used across multiple puzzles. Rather than give the table directly, a seprate puzzle, like symbol algebra. And rather than give a message of symbols outright, the symbols and order can be extracted from another puzzle, like the grid lookup.

Pigpen Cipher

The pigpen cipher is a simple and well-known substitution cipher that uses lined grids to define unique symbols for each letter in the alphabet. There are several variants of the pigpen cipher, but a common substitution table looks like this.

Each letter in the pigpen cipher is defined by the border of its region. For example, E is in the middle of the grid, surrounded by borders, so it is represented by a square. B, above it, has an open border on the top, so it is represented by a box with an open top.

Ultimately, this leaves a code that looks like this.

    ,

   

   

   

   

   

   

   

   

   

   

.

Using the pigpen cipher above, the shapes can be matched to letters that spell out this secret message.

Because the pigpen cipher is quite well-known, there is a good chance that players will already be familiar with it and will be able to decode a message without a provided substitution table. Thus, consider providing the decoding table before providing the message.

Morse Code

Morse code is the famous encoding of letters using a sequence of “dots” and “dashes.” This code is useful to send a message using a mode of communication that can only transmit on and off. The signal is turned on momentarily for a dot and a little longer for a dash.

Morse code was originally used to transmit messages over an electric telegraph in which a sender closed a circuit on one end to activate a clicker on the other end. But Morse code can also be communicated with beeps of sound or flashes of light.

Here is a table for the international Morse code.

Although some people have memorized Morse code, most have not. So, you should always provide the Morse code table unless you are very sure that the players have memorized it.

Although you could provide a Morse code message on a piece of paper drawn in circles and lines, the fun part of Morse code is to hide it in a beeping or flashing item. This can be trickier to create than a simple printed message or image. A straightforward way to provide a Morse code message is to create an audio or video file that can be played on any number of devices.

A fun thing to do with a Morse code message is to hide it in some unrelated sight our sound. Spell the Morse code message in car horn honking, a dog barking, or any other theme-appropriate repetitive sound. Or maybe that flashing light on a buoy or satellite has a flashing pattern.

Players inexperienced with interpreting Morse code are likely to find the task difficult. Therefore, it is best to keep the message short (one or two words at most) and to give the code out slowly.

Braille

Braille is an alphabet designed to be read by touch rather than sight. A “letter” in Braille is represented by a matrix of dots 2 wide and 3 high. Braille is typically written by embossing paper or another material to create some combination of bumps in this 2x3 pattern. This makes it possible to interpret the letters by feeling the bumps with a finger pad.

One way to force players to read a Braille message without looking at it is to paste the embossed Braille inside of a closed box with a hole. To read the message, players must reach a hand in through the hole and feel for the message.

Although not the original point, Braille messages can also be read visually. To make this more challenging, hide the Braille letters in objects or images that naturally have grids. Here is an example of hiding a Braille message in the windows of a skyline.

The image looks like ordinary drawing of buildings. But a closer look reveals that all the windows are grouped in 2x3 grids like Braille letters are. The lit windows encode in each of these grids a Braille letter, spelling out “I Spy”.