aka 'Night Line'
Probably a better one for outdoors. Particularly good as a night activity where you can decide whether blindfolds are still required.
Using lots of string weave a course around an area indoors or outdoors, going over, under through various obstacles, etc. Participants are blindfolded and either with a seeing partner or without any help have to negotiate themselves around the course by only following the string.
It’s not unknown for rope trails, when outdoors, to lead through streams or for people to be strategically placed around the course with water pistols 🙂