The following is a list of common Zen terms, along with some rather whimsical interpretations of them in the context of the game of Zendo.
Koan—In Zen, the term “koan” (pronounced KO-ahn) refers to a short enigmatic riddle or text which is given to a student to meditate upon. Koans often seem paradoxical or nonsensical; their aim is to “break the mind of logic”, thus preparing the student’s mind to make the leap of insight that lies at the core of Zen. The most well-known Zen koan is “What is the sound of one hand clapping?” In the game of Zendo, each group of Icehouse pieces poses the riddle “Does this configuration have the Buddha-nature?”, and is therefore also a kind of koan. Although the answers to Zendo koans are always logical, they often seem capricious and nonsensical to the students, exhausting their logical capabilities and leading, perhaps, to a moment of insight.
Mondo—A question-and-answer session led by a Zen Master, often in a group setting. The Master may ask koan-like questions in rapid succession, in an attempt to throw the students off-balance and lead them to a moment of insight.
Katsu—A Zen word which has no exact meaning. Masters often shout “katsu!” to startle students into attention, or even into enlightenment. It it sometimes translated as “wake up!” I’m not sure if the similar-sounding term “kotsu” is etymologically related; it refers to the stick that Masters use to hit, poke, or prod students who are falling asleep during meditation. In the game of Zendo, the Master shouts “katsu!” when a student knocks over pieces, or otherwise disturbs the board in some fashion.
Sanzen—An interaction between a Master and a student, usually relating to the student’s progress on a koan. In Zendo, the term “sanzen” may be used to refer to the portion of a player’s turn when he or she spends stones to guess the Master’s rule.
Jakugo—A phrase or expression that summarizes a student’s understanding of a koan. In Zendo, this term could refer to the actual guess that a player makes when paying a stone to guess the rule.
Satori—A state of mind which is often associated with “enlightenment”. It involves a recognition and understanding of Buddha-nature. This is, of course, the goal of the game of Zendo.
Wato—A response to a koan, which may be a word, a phrase, or even a gesture. In Zendo, the “response” to a koan is a black or white stone (or perhaps, the act of revealing such a stone from a closed fist). Therefore, the black and white stones may be thought of as “wato stones”.
Zafu—The small cushion that the Zen student sits on during meditation. This doesn’t really have much to do with the game of Zendo, but isn’t “zafu” a cool word?
Zendo—A meditation hall. More generally, any place where people go to practice Zen (or play Zendo). For the enlightened, the entire world is a Zendo.