Games Showcase: Zendo

Zendo is a multiplayer game of inductive logic that runs on very low spec hardware; to be precise, lego bricks or similar.

You also need three types of small marker: for example black, white and green stones.

Gameplay

Players take turns to be the “Master” for a round, in the sense of “Zendo Master”. This role is like the question setter in 20 questions.

Instead of a question, the Master thinks up a predicate over structures in whatever construction set you’re using.

I’m going to give an example round using ASCII art bricks as a construction set.

First in the Master role is Alice.

Having thought up a predicate about ASCII art bricks, Alice must build two structures—referred to as koans—of which one satisfies the predicate, and one of which does not.

The one that satisfies the predicate is said to “have Buddha nature” and is marked with a white stone; the other does not, and is marked with a black stone.

So here the koan on the left has Buddha nature, and the one on the right does not.

Player Builds a Koan

To play out the round, the players take turns.

On his turn Bob must first build a koan of his own:

And then declare either “Master” or “Mondo”.

In our example, Bob declares “Master”.

“Master”

“Master” means “Master, does my koan have Buddha nature?"

The Master answers with a white or black stone; in our example Alice marks the koan with a black stone to signify that it does not have Buddha nature, and it is added to the set:

That ends Bob’s turn. Eve plays next. She builds her koan:

Then declares “Mondo”.

“Mondo”

This means, “let’s see what we have learned”.

Each player secretly evaluates whether the new koan has Buddha nature, by holding concealed a black or white stone. Then the Master reveals the truth and anyone who was correct is awarded a green “Guessing Stone”. The koan is labeled then added to the set; this time it does have Buddha nature.

Eve evaluates the koan correctly and wins a Guessing Stone.

Guessing

At the end of a player’s turn they may spend Guessing Stones, if they have them; each buys a guess at the predicate.

Eve guesses “a koan has Buddha nature if it is four blocks wide”.

Guesses must be consistent with every koan that has been marked, and other players can help catch mistakes if they wish. For example if the guess had been “a koan has Buddha nature if it is two blocks high” then this guess would have been rejected without it consuming the guessing stone, because there is a counter-example visible: a koan with Buddha nature that is one block high.

If the guess is correct, that player “wins” and the round is over.

If the guess is not correct, the Master must build a koan that proves it is not correct: they may either choose to build a koan with Buddha nature that does not satisfy the guessed predicate, or a koan without Buddha nature that does satisfy the guessed predicate.

Alice builds and labels:

Thus proving that it is not necessary for a koan to be four blocks wide for it to have Buddha nature.

A proof in the opposite sense could have been:

Thus proving that it is not sufficient for a koan to be four blocks wide for it to have Buddha nature.

Endgame

Bob takes his turn. He has a good idea what the rule is; he constructs a koan that he is sure about, declares “Mondo”, wins a Guessing Stone then wins the round with a correct guess.

Perhaps you also have a guess at the predicate!

Further Rules

Predicate Scope

It must be possible to evaluate the predicate without reference to anything outside the koan, so for example orientation must not be considered.

Simple predicates work best, and it is useful to have a list of aspects that can be considered: count of pieces, layers, colours, and so on.

Finite Pieces

If a player does not have enough pieces to build the koan they wish to build, they may request pieces from the Master. Then, the Master destroys koans selectively to provide the pieces. They should leave intact the koans that make the most important statements about Buddha nature.

Conclusion

Relaxed

Zendo is a very relaxed game—almost cooperative. While one player must “win” a round, points are not kept. The Master “wins” if they come up with a predicate that leads to a fun round.

Recommendation

It’s often possible to find a box of lego bricks or similar, and the game is very easy to explain and to pick up; so it’s a good one to pull out for impromptu gaming sessions. Enjoy!

Credit

Zendo was designed by Kory Heath and published a little over 20 years ago by Looney Labs, who also offer expansion sets with additional mechanics.

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