After the first move is made in a game that uses the pie rule, the second player must select one of two options: Depending on the game, there may be two ways to implement switching places.
The use of pie rule was first reported in 1909 for a game in the Mancala family.
The rule can be applied to other games which are otherwise solved for one player, such as Gomoku or Tablut.
[4] The rule gets its name from the divide and choose method of ensuring fairness in when dividing a pie between two people: one person cuts the pie in half, then the other person chooses which half to eat.
This rule acts as a normalization factor in games where there may be a first-move advantage.