There need to be enough people to make a reasonable sized circle but there is no number restiction. All chanichim should sit in a circle on chairs with 1 playing card in their hand. The madrich/a calls out a suit e.g. clubs and all people holding a card of that suit move one chair to the right. If the person next to them have not moved they have to sit on top of them. If there is someone on your lap, you cannot move, even if your suit is called. The game can continue for any amount of time.
This is also a really good way to mix up a group in a circle if you need - instead of people sitting on each other, they just move to the next available seat.