High wall is a group dynamics game for several groups of around 6 people each.
You don't need any equipment, but some adhesive tape (different colors for all the teams) would be helpful.
You need a high wall for this game. A higher tree could also be used. However, the wall should be quite flat and should not provide any possibilities to "climb" it.
The task of the group is to climb as high as possible on the wall (if you have adhesive tape: to stick the tape as high as possible without using any other equipment). The groups first get some time to think about the task, and then a short time to execute their solution.
Ensure that all teams get the same time to think about the task. This works best if all teams can execute their solution at the same time (provided the wall is wide enough to support all teams at the same time).
Of course, you also have to ensure that none of the participants is hurt. Don't put too many players in one team (that limits the hieght automatically), or use additional players that secure the participants while "climbing".