[Icehouse] Four-house Zendo

[Christopher Hickman]

> "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.