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I have been tasked with coming up with a puzzle given the following constraints:

1. Users (possibly 200 in all) will arrive at a fixed location and see a portion of the puzzle, which will be common to all users.


2. There will be nobody present at this location to offer hints, or explanations.


3. There should be multiple (between 5 and 20) different solutions given the same common information. Each user will be given some additional information that combines with the common information to yield a solution. (Given constraint #2, this is mostly to prevent cheating between users. It is acceptable for multiple solution paths to eventually yield the same solution as long as users know they can't simply copy off the person next to them.)


4. Users may be given a prop or two, but they should be simple/cheap to acquire/manufacture. I have no desire to provide functioning copies of the Enigma machine to each of 200 possible users.


5. Wordplay and culture-specific knowledge should be avoided.


6. Internet access can not be assumed, and users are not avid puzzlers (so probably nothing more complicated than a standard Caesar cipher should be involved).


7. Time to solution should be between 5 and 15 minutes. Faster isn't an issue, but neither should people be stuck for 60+ minutes.


8. My time is valuable, as is that of the people who will check the solutions. The various solutions should be relatively quick to create and to confirm.

I have basically no idea what kind of puzzle would satisfy all of the constraints.

In this question I saw a reference to using different-colored cellophane to create different solution paths. This is very cool, but it would seem that only three different paths are possible (red/green/blue, or magenta/cyan/yellow), where I need at least five. A puzzle using a grid-based map as in this puzzle would seem to offer many different (and easily-checked) solutions, but then I would need to come up with a set of clues for each desired solution.

I am not (knowingly) requesting a ready-made puzzle, but rather some guidelines or puzzle types that combine common information with user-specific information to arrive at user-specific solutions.

Would a physical puzzle of some sort be appropriate? I'm thinking of something like a maze, with a lot of endpoints, but missing the middle section. Each user is given a piece of card with the centre of the maze on it, but each user's card is different, and leads them to a different endpoint.

The endpoint could just be a password/phrase to be communicated to the person checking the solution, or could be a further small puzzle that needs to be solved (e.g. simple cipher or anagram).

Or, if you don't want to design a whole maze, perhaps a word spelled out using a seven-segment display:

 _ _ _ _ _ _
| |_| | |_| |_ |_ 
|_ | | | | | | |_

(using a lowercase R)

If you provide only the top half on-site,

 _ _ _ _ _ _
| | | | | | | | 

you can give different bottom halves to different people, creating different words:

 _ _ _ _ _ _
|_ | | | |_| |_ | 
| |_| | _| |_ |

 _ _ _ _ _ _
| | | | |_| |_ |_ 
|_ |_| | | _||_

 _ _ _ _ _ _
|_ | | | | | | |_ 
|_ | | |_ |_| | |_

Neither half can be interpreted on its own; you need them both to get the final word.

(I wrote a quick Python script to find words that would match a given top segment. Other words for this particular one include CORNER, ENCASE, EARNER, CASPER, and a few more obscure ones.)