Seat participants in a circle on chairs. Select a person to be in, say Victor. Victor stands up in the middle of the circle, and has to try to sit on the empty seat, while everyone sitting tries to block him from sitting. They do so by the person to the left or right of the empty seat moving to fill it when Victor gets close (they should not have to use their arms). This usually means everyone in the circle is busy filling the seat to their left/right while Victor chases the hole. Someone might then choose to change direction or pause briefly, but this is a risk... whoever is responsible for letting Victor sit, then has to take his place.