A player's turn consists of dropping marbles, one at a time, in through the holes at the top of the apparatus. You cannot drop another marble until all the others have stopped moving. As soon as any marbles drop out at the bottom of the apparatus, they are all returned to the current player, and it becomes is the next player's turn.
If, at the end of a player's turn, all their marbles are the same colour and there are at least five of them, then that player has won.
If a player runs out of marbles, and is therefore unable to to drop one in at the top when required to do so, then that player has lost, and the game is over.
If, at the start of a player's turn, they have few marbles, and there is no way that they can use them to cause any to drop out at the bottom, then they may pass. It then becomes the next player's turn. If, however, there is a way that they can cause at least one marble to drop out at the bottom (other players may point out such a way), then they must play in the usual way.
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