You need a ball to play the game (a soccer ball, or similar). Each participating player except one needs his own tree to defend. When no trees are available, you can use other objects for that purpose, like a ton, a large box, an empty trash can, etc.
One player is selected to be the hunter. The other players all select a tree. When there are a lot of participants, you can play with several hunters simultaneously.
The hunter has the ball. He may only touch the ball with his feet. His job is to hit a tree with the ball. The other players try to defend their trees so that the hunter cannot touch a tree with his ball. They may defend the trees with all their body parts (but they may not keep the ball, just kick it away). However, while defending their tree, they always need to touch their tree with at least one body part.
When the hunter successfully shoots the ball against one tree, he and the defender of that tree switch positions, so the unlucky defender becomes the new hunter.
If the hunter does not succeed, after some time, he may shout a certain code word. Then, all players have to select a new tree to defend. The hunter may also select a tree. On unlucky person will fail to reach a tree in time: that is the new hunter.