Escape Room: Plastic Film Code
When players walk into your escape room, one of the things they will notice is an 8 by 10 (or whatever size) piece of paper on the wall with letters on it that looks like the following:
In another location in the room, the group will find a transparent film with numbers written on it in the same pattern (but shifted slightly to the right) as the sheet on the wall.
They are to figure out to superimpose the transparent film on top of the posted letters to get the code. It will appear like this when the plastic film is placed on top of the letters:
You can use this code anywhere in your escape room to give a message for the group to decode. Such as making a hint to look for a secret pencil, a secret book, etc. Or, you can code one of your pieces of evidence, etc.
Props needed for this scenario:
An 8 by 10 sheet of paper (or whatever size you wish) with random letters written (or printed) on it.
The same size of plastic film (i.e. overhead projector film) with numbers that correspond to the letters, forming a code. In the example above, A=2, B=5, F=7, and so on.