I almost have Zendo! I ordered some pyramids that should arrive tomorrow, and just bought some glass marking stones.
This is a fun logic game. One person is chosen as the master. The master creates a secret rule or test. You win the game by being the first player to correctly guess the master’s rule. The rule describes valid arrangements of the pyramids. An example of a rule is: “the arrangement must have at least one green pyramid”.
To begin the game, the master creates two example arrangements, one that follows the rule, and one that does not follow the rule. The master places a light marking stone beside the arrangement that follows the rule, and a dark marking stone beside the arrangement that does not follow the rule.
Players then, in turn, create arrangements and ask the master to mark them. The master marks arrangements that follow the rule with a light stone and marks those that do not follow the rule with a dark stone. By doing this, players gain information about the rule.
There are special guessing stones that you need to obtain if you want to make a guess at the rule, and there’s a special way to acquire these. It’s all explained in more detail at the Wikipedia article.
When you finally are ready to make a guess at what the rule is, you spend one guessing stone and tell the master your guess. If you are correct, you win the game. If your guess is incorrect, the master constructs a counter-example, and marks it appropriately. The master either builds an example that your rule would have marked light, but is in fact dark, or builds an example that your rule would have marked dark, but is in fact light.
Zendo’s a good game if you’re looking for something abstract. There’s no board, so it’s very portable. All you need is some space on a table to set up the examples. Depending on the difficulty of the rule, how good the players are at guessing, and how much information comes from the master’s examples, each game should take between 5 and 20 minutes. There’s as much fun in being the master as there is in being a player. The pyramids cost $24 from Looney Labs during their closeout sale, and the stones about $10 from a craft store.