zendo

https://en.wikipedia.org/wiki/Zendo_(game)

Zendo is a game of inductive logic designed by Kory Heath in which one player (the "Master") creates a rule for structures ("koans") to follow, and the other players (the "Students") try to discover it by building and studying various koans which follow or break the rule. The first student to correctly state the rule wins.

Neat idea for a game, there's no need to buy anything - you could just use scraps of paper if you wanted.

Found it via regexle, which is a fun (if extremely nerdy) version of Zendo in which there is a hidden regular expression and you have to find it via guessing strings or regular expressions.