Twelve men's morris problem #517

The task

To move

Dark

Difficulty

Hard

Goal

win in 3

All men are on the board and the game is in the movement phase: Light has 4, Dark has 7. A hard problem: not a mill but the whole game, usually by leaving the opponent with two men or without a move.

What to look for

• Movement phase: men only step to neighbouring points, so check which of them are actually free.
• Two threats at once: one move should leave two mills, lines or captures that cannot both be stopped.

How the answer is checked

There is exactly one first move that forces the result; any other first move allows the defence to escape. Moves that keep the forced result are accepted later in the line, and a move that loses it is taken back with a short note.