What is Nine Men's Morris?
Nine Men's Morris is a classic board game where two players place and move nine pieces each on the 24 points of three nested squares, removing one enemy piece every time they line up three of their own. It is also called the mill game, merels, or Mühle in German.
A line of three is called a mill. The board has 16 lines that can become mills, so the game mixes the line building of five in a row with the capturing of chess. Boards have been found carved into a Viking ship and into the stone cloister benches of medieval English cathedrals, and Shakespeare mentions the game in A Midsummer Night's Dream. Here you can play the computer on easy, normal or hard, or play a friend on one screen.
What are the three phases?
Every game moves through placing, moving and flying. Each player changes phase on their own, so one side can be flying while the other is still sliding.
| Phase | When | What you can do |
|---|---|---|
| 1. Place | While you still hold pieces (the first 18 turns) | Put one piece on any empty point |
| 2. Move | After all nine are placed | Slide one piece along a line to the next empty point |
| 3. Fly | When you have only three pieces on the board | Jump to any empty point, lines do not matter |
A mill made in any phase removes one enemy piece. The trays beside (or above and below) the board always show the pieces left in hand and the current phase of each side.
Which piece can I remove after a mill?
Pick any enemy piece that is not part of a mill. Pieces inside mills can be taken only when every enemy piece is in a mill.
When you close a mill, golden light runs along the groove and only the pieces you may take blink with a red ring. Tap one and it cracks and shatters. Two mills made at once still remove only one piece. Opening a mill and closing it again on your next turn counts as a new mill, and that back and forth is the strongest attack in the game.
How do you win or draw?
You win when your opponent is down to two pieces, or has no legal move on their turn.
| Ending | Result |
|---|---|
| Opponent has only two pieces left (board plus hand) | Win |
| Every opponent piece is blocked | Win |
| 50 moves in the moving phase without a removal | Draw |
| The same position appears three times | Draw |
In the 1990s the game was solved by computer: with perfect play from both sides, Nine Men's Morris is a draw. One careless move is all it takes to decide a game.
Where should I place my first piece?
The best first spot is the middle point of a side on the middle square, where four lines meet. It has four neighbours for later moves and sits on two possible mills.
- Value room to move over early mills. Rushing mills while placing often leaves your pieces stuck in the moving phase.
- Take corners late. A corner has only two neighbours and gets trapped easily.
- Block every open two at once. Putting your piece on the third point is the surest defence.
- Build a double mill. A shape where one piece shuttles between two mills scores every turn and cannot be stopped.
- Watch out when your opponent flies. They can land anywhere, so fill the empty point of any line that holds two of their pieces.
How do the computer levels differ?
Easy looks one move ahead and sometimes plays oddly, Normal reads four moves ahead in 0.3 seconds, and Hard reads five to nine moves ahead within one second.
Hard uses iterative deepening alpha beta search and understands the threefold repetition draw, avoiding repeats when it is winning and aiming for them when it is losing. Learn the feel of mills on Easy, then move up when Normal stops being a challenge. Your wins are counted per level on the title screen.
Controls
- Touch and mouse: while placing, tap a sparkling empty point and a piece flies in. While moving, tap your piece and then a sparkling point, or drag the piece onto the point.
- Removing: after a mill, tap one enemy piece with a blinking red ring.
- Keyboard: arrow keys or WASD choose a point, Enter or Space places, selects or moves. Ctrl+Z or U undoes, Esc drops the selected piece.
- Two players: Ivory and Obsidian take turns on one screen. The tray of the side to play glows gold.
Switch your side to Obsidian on the title screen to let the computer move first. Wins and the sound setting are stored only in this browser and are never sent to a server.