It’s a community treasure hunting game. A person hides something, then posts GPS coordinates and/or clues to lead you there. Often the hidden item is a sealed container so people can leave log books or unique trinkets. Some of the trinkets have serial numbers you can use to see where they’ve traveled.
I haven’t done it in years, but I remember it being a lot of fun. Hunting for caches led me to a bunch of interesting new places that I would never have explored otherwise.
I empathize with your situation. I’m in the same boat. Even with hundreds of subscribers, if everyone’s lurking then the community gets stale and withers. Becoming a one-person content machine isn’t sustainable.
Though on a brighter note, with this post you just gained a subscriber to your community. Browsing through it reminded me of how fun geocaching was. I just dusted off my old geocaching.com account from a decade ago. I’ll have to take my kids out and see what we can find!