> "Contains at least one vertical piece in your favorite color" is OK > if everyone is OK with player-specific metarules, and the favorite > colors of all players are well-known. No. Spock doesn't know players' favorite colors. You can only base rules on objectively observable characteristics of koans. > Of course, that tends to lead to a longer game, since each koan would > now have to be considered in the context of the guesser, and not > simply on its own. Zendo geeks only. No. If the marking of a koan is dependent on who built it, that's a red-flag that you have an invalid rule.