What is Twelve Men's Morris?
Twelve Men's Morris adds four diagonal lines to the Nine Men's board. Each one runs from a corner of the outer square through the corner of the middle square to the corner of the inner square. Each player has twelve men. White moves first.
The diagonals count as lines in every way: men slide along them, and three men of one colour on a diagonal make a mill, so the board has 20 possible mills instead of 16. Making a mill removes one of the opponent's men, as in Nine Men's Morris.
With twelve men each, the 24 men can cover all 24 points. If the board fills up during placement, nobody can move and the game is a draw. Otherwise play goes on as in the standard game, and flying for a player down to three men follows the option in the table setup.
Rule changes
| Rule | Standard Nine Men's Morris | Twelve Men's Morris |
|---|---|---|
| Board | Standard Nine Men's Morris24 points on three nested squares, joined at the midpoints of their sides. | Twelve Men's MorrisThe same 24 points, plus four diagonals that join the corners of the three squares. Men slide along the diagonals too. |
| Men per player | Standard Nine Men's MorrisNine. | Twelve Men's MorrisTwelve. |
| Where a mill can be made | Standard Nine Men's MorrisAlong the sides of the three squares and along the four lines that join their midpoints: 16 possible mills. | Twelve Men's MorrisThe same 16, plus the four diagonals: 20 possible mills. |
| A full board | Standard Nine Men's MorrisCannot happen: 18 men leave at least six points empty. | Twelve Men's MorrisIf the 24 men fill every point during placement, the game is a draw. |
| Flying | Standard Nine Men's MorrisA player with three men left may move a man to any empty point. It is on by default and can be switched off in the table setup. | Twelve Men's MorrisThe same. |
History
Twelve Men's Morris belongs to the same old family of mill games as Nine Men's Morris. Its board, with the four diagonals, is best known today from southern Africa, where a closely related game called morabaraba is played in South Africa and Botswana, with a variant in Lesotho. Morabaraba goes by many names, among them mlabalaba, mmela and umlabalaba, and it is played as a competitive mind sport, with world championships held since 1997.
Morabaraba has some rules of its own, so the game here keeps to the rules of Nine Men's Morris and only adds the diagonals, the extra men and the draw on a full board. In 2014 Gábor Gévay and Gábor Danner computed full solutions of Nine Men's Morris, Lasker Morris and morabaraba. They found that most morabaraba starting positions in which both players place the same number of men are wins for the first player, while in the other two games such positions are usually draws.