The Polish Tourism and Sightseeing Society promotes tourism and sightseeing, and one of its means is granting badges for various achievements, such as walking above 250 km on tourist routes, participating in 5 orienteering contests, visiting one of UNESCO memorials, visiting national parks and nature monuments, visiting historical places etc.
Well, you all participate in StackExchange sites, so I think I don't have to explain the rationale behind badges ;)
I wonder if something like that is functioning in Western Europe, especially in Germany.
There are EarthCache Discovery Awards, which are worldwide, which means, they can be achieved also in Germany. Generally, the whole Geocaching falls into that concept.
But it's not exactly what I want. I'm looking for some challenges connected with visiting trails, hiking, etc.