Zendo is terrific: https://en.wikipedia.org/wiki/Zendo_(game) One player thinks of a secret rule, and the others have to guess the rule by building little sculptures.
It's best played with a set of Icehouse pieces, which pack pretty small and can be used for a whole bunch of other games too. You don't need Icehouse pieces, though, you can also play Zendo with coins, matchsticks, etc.