The beginning of a game of Zendo. According to the marker stones, the koan on the left does not follow the Master's rule, but the one on the right does.
|Age range||All ages|
|Setup time||< 5 minutes|
|Playing time||5–30 minutes|
|Skill(s) required||Inductive reasoning
Zendo is a game of inductive logic designed by Kory Heath in which one player (the "Master") creates a rule for structures ("koans") to follow, and the other players (the "Students") try to discover it by building and studying various koans which follow or break the rule. The first student to correctly state the rule wins.
The rules were published in 2001 after more than a year of playtests and changes. A boxed set of the game was released by Looney Labs at the 2003 Origins Game Fair but is now out of print. The set contained 60 Icehouse pieces in red, yellow, green, and blue, 60 glass stones and a small deck of cards containing simple rules for beginners. Zendo is also published in Looney Labs' Playing with Pyramids, a book of rules and strategies for a dozen popular games playable with Icehouse pieces. The rules are also conveniently available on Wikipedia.
Zendo can be compared to the card game Eleusis and the chess variant Penultima in which players attempt to discover inductively a secret rule thought of by one or more players (called "God" or "Nature" in Eleusis and "Spectators" in Penultima) who declare plays legal or illegal on the basis of their rules.
Zendo is designed for three to six players. One is the Master and the others are Students.
A game will require:
- A few dozen building pieces. The game was designed for Icehouse pieces, but Lego bricks, Magnetix, coins, numbers and words can be used.
- Two dozen "marking stones", half white and half black. Alternatively, the Master may designate two halves of the playing space as "white" and "black" and move each koan to the appropriate side.
- At least a dozen "guessing stones". These are usually represented by green stones, but coins work just as well.
- Two "answer stones" for each player: one white, one black.
Choosing a rule
The Master must devise a secret rule for koans to follow. Rules may refer to anything about the pieces or their contact or alignment with the playing surface, but may not refer to external conditions such as the posture or words of any player, or their alignment relative to anything outside the koan. A koan will "have the Buddha-nature" and be marked white if and only if it complies with the rule; otherwise, it will be marked black. Rules should be formulated in very specific terms so that the Master does not accidentally misjudge koans or wait until the middle of a game to ponder an ambiguity.
Some example rules, listed in increasing difficulty, are:
- A koan has the Buddha-nature if and only if it has at least one blue piece.
- A koan does not have the Buddha-nature if and only if it has any green pieces.
- A koan has the Buddha-nature if and only if it has an odd number of blue pieces.
- A koan has the Buddha-nature if and only if the number of blue pieces touching at least one green piece is odd.
Rules are often harder for Students to solve than the Master expects, and the designer suggests it is better to make a rule that is too simple, than too complicated, as an extremely short game is not as frustrating to Students as an extremely long one.
Once the rule is created, the Master will create and mark one white koan and one black one. This pair will give the Students some idea of where to start in inducing the rule. A helpful pair has many similarities, and an unhelpful one has few or none. The Master is encouraged to ask the Students whether they want a helpful or unhelpful pair of initial koans, but the Master should decide how helpful he or she wants to be.
After this, the Master will take the role of a moderator and judge, and the Students will begin to play, beginning with whomever the Master picks and proceeding clockwise.
In a turn, a Student should:
- Build a koan using pieces from the box. Koans may be built in any way as long as they do not touch other koans or objects other than the table. If a piece the Student wants is not available, he or she may ask the Master to break a koan down. The master is encouraged to consider the input of other players in making a decision and may deny the request.
- Say "Master" or "Mondo". "Master" is a request for the Master to mark the new koan white or black. "Mondo", on the other hand, requires all Students to guess whether the new koan is white or black. Each Student, including the one who called Mondo, should hide an answering stone in one fist, hold that fist over the playing field, and reveal the stone when everyone is ready. The Master will then mark the koan appropriately and award a guessing stone to each Student who guessed correctly.
- Guess the Rule (optionally) by giving a guessing stone to the Master and clearly stating a guess of the rule. If the guess is ambiguous, the Master will ask the Student questions about the guess until it is clear. The Master will return the guessing stone if any koan on the table violates the guess, or if the Student is unable to articulate a guess which is clear to the Master. It is the Master's responsibility to make sure guesses are unambiguous and not contradicted by existing koans, but help from other Students is encouraged. Once a clear guess is made, the Master will try to disprove it by building and marking either a white koan which the guess would rule black, or a black koan which the guess would rule white. If the Master disproves the guess, the Student may repeat the guessing process until he or she runs out of guessing stones.
If a Student makes an official guess which the Master cannot disprove, that Student has discovered the rule, achieved enlightenment, and won the game.
- Zendo won the 2003 Origins Award for "Abstract Board Game".
- Zendo was named one of the 2005 Mensa Select games by American Mensa.
- Heath, Kory (8 September 2004). "Zendo—Design History". Retrieved 2010-02-23.
- Zendo Details and Clarifications, as found on the game designer's website.
- "Origins Award Winners (2003)". Academy of Adventure Gaming Arts & Design. Archived from the original on 2008-04-30. Retrieved 2008-08-15.
- "Past Winners of Mensa Select Awards". Mensa U.S. Retrieved 2008-08-15.