This is a traditional Chinese boy's game, similar to marbles. Children "win" coins in this game, so you will need to decide whether to play with real coins as the prize or to claim them back at the end!
You will need:
Each child holds a coin up against a wall, with its edge touching the wall, and lets it drop.
The child who's coin rolls furthest away from the wall then gets the first turn. He picks up his coin, marking its place with his foot (which he must not move). He then pitches his coin at the other coins lying around. If he touches a coin, he wins it and has another go. If he misses, everybody picks up their coins (or, if they have lost their coin, brings out another one or drops out) and starts again.