Get people into groups of 6-9. 7 is the ideal number because it is guaranteed statistically to unwind every time, whereas there is a small chance the groups of 6, 8, and 9 won’t completely unwind every time. (Groups larger than 9 don’t work well because people are too far apart to link arms, and smaller than 6 doesn’t offer enough variation/complexity.)
Have each person raise their right arm and reach across the circle and connect arms with someone across from them. It cannot be someone directly next to them on either side.
Then have them raise their left hand and connect arms with someone else in the circle. It cannot be with the first person they have already connected with or someone directly next to them on either side.
Then ask the groups to maintain connection and try to unwind the knot so that they come back into an open circle.
They will have to negotiate, communicate and compromise in order to make this happen. Some groups unwind very quickly and easily and some take more time. If one group finishes quickly, you can have them play another round while other groups are completing. If a group truly gets stuck and can’t unwind fully, you can have them try again from the beginning. The vast majority of the time it does unwind fully, and even when it doesn’t, the lessons learned along the way are just as powerful and applicable.