Wife and I did some geocacheing before, quite enjoyed it, although we did look like weirdos loitering for quiet periods then rummaging around an old bridge on a relatively populated woodland walk...
Slight deviation would be escape rooms. I think we've only done one but really enjoyed it/the different thinking around various tasks.
I met some people that were doing something called "Treasure Trove" if memory is correct... basically it takes you all around cities and you have to find clues on various plaques.
If your idea is to do your own sort of tour, I guess there are multiple ways it could be done.. .
App based to give you the clues/map (like geocacheing) and either a physical find (like geo caches) or some sort of "you've arrived" notification on a phone...
If you wanted to avoid tech then I'd guess you'd still need to have some sort of website for basic exposure and basic "rules" or guidance.. maybe combining it with OS maps and giving off various clues... perhaps this could work in conjunction with an app/website, whereby someone has to input maybe a lat and long to get the next clue/destination, or if the location has some sort of specific history to it or specific name... Or just have the whole load of locations and people can go in whatever order they want, return the "answers" to any question and receive a thumbs up emoji haha.. (or a t shirt) or whatever you want...
I seem to recall as a youngster doing so.ething where there was these spiked stamps? You reach a destination and clip your card and each clip has a different pattern (so as to not cheat), I think that was navigation based but can't for the life of me recall it..
