Jail Break

1. Mark a jail 23 metres wide and 27 long. Split the group in two: the prisoners, each with a ball, inside the jail, and the guards, without a ball, spread around its four sides.
2. Guards stay on the boundary line. They may slide along it and round the corners to block a prisoner, but never step into the jail or chase anyone outside it.
3. A prisoner breaks out by dribbling over the line past the guards. Then they dribble back in anywhere, and the next break-out has to go through a different side.
4. A guard who wins the ball plays it back into the jail, and the prisoner goes after it and tries again.
5. After 60 seconds, prisoners and guards swap. Each prisoner counts their own break-outs and tries to beat that count in their next round. With more than 14 players, mark a second jail.

The prisoner has four sides to choose from and a handful of guards who cannot be everywhere. So the head comes up: which side has the biggest gap between two guards, and which guard is busy with another prisoner? A guard can only move along the line, so a prisoner who comes in at an angle makes the guard pick a side, then cuts the other way and accelerates past. Two prisoners going at the same stretch of line at the same time almost always means one of them gets out. After every break-out the side you just used is closed to you, so you turn, look again and choose the next one. The guards decide which prisoner to step towards, and two guards on one side have to split the line between them rather than go for the same player.