Nine Men's Morris is a relatively simple strategy game for two players. The game was almost certainly known by the Romans, and was possibly the most commonly played board game in Europe throughout the medieval and Tudor periods, with many examples of boards scratched into stonework, on wooden pews or seats (e.g., in Westminster Abbey), or, in one example, on the top of a barrel on the Mary Rose. The game is referred to by Shakespeare in A Midsummer Night's Dream. The game has remained popular into the 21st century, so rules are well attested.