The group stand in a group in a circle. They are ‘on the hill’.
When the leader says ‘in the swamp’ the group all take a step forward. When the leader says ‘on the hill’ they take a step back. Explain this at the start. Encourage them to move with confidence. The leader can say something like ‘on the potato!’ or something else, to confuse the group.
If anyone moves when they aren’t supposed to, they are ‘out’