Nim is a pure strategy game for two players. On each turn, players remove an option until finally no choice remains.
Game options might include:
- How many stones to take from a pile.
- Which position to claim on a gameboard.
- How far to count in a given sequence.
The rules can vary at the players’ whim (as long as both players agree). How many possibilities do you start with, what are the rules for removing options, and how do you win or lose the game? Everything is open to change. And with every tweak, players must reanalyze their strategy.
Denise Gaskins' Let's Play Math 