Simply get five sheep and dress them up in rugby shirts. Then get the players (in this case 500 children) to chase the sheep around a rugby pitch trying to wrestle them to the ground. The first group of players to successfully ground and immobilise a sheep are the winners. Sheep Tackling has been a popular half-time entertainment at rugby matches in parts of New Zealand but is now banned following criticism from The Society for the Prevention of Cruelty to Animals.
I am indebted to Wayne Skipadoo (Strange Games Antipodean Correspondent) for information on this excellent game
strange games no:112
web: BBC News item on Sheep Tackling