Nine Men's Morris

Nine men's morris is a strategy board game for two players, dating back to at least the Roman Empire. It is also known under many other names, including nine man morris, mill, mills, merels, merrills, and in North America as cowboy checkers, and its board is sometimes printed on the back of checkerboards. It is a solved game, meaning its optimal strategy has already been worked out, and perfect play by both sides is known to end in a draw. The three main variants of the game are three, six, and twelve men's morris.