Playing Zendo

"With Zendo, one player takes on the role of “Master” for the game. Everyone else is a player. The Master determines a rule for the game and then constructs two “koans” from Icehouse pyramids. One koan exhibits the rule and one koan does not exhibit the rule and they are marked with a white and black stone, respectively, to represent this. A koan that represents the rule is said to have the Buddha-nature, while one that does not meet the rule’s criteria, does not have a Buddha-nature. The players are not told what the rule actually is though. (It can be simple or complex, such as “A koan has the Buddha-nature if it has at least one green pyramid and exactly one upright pyramid.”)"

http://www.arcanology.com/2008/05/10/playing-zendo/