Nine Men's Morris

Overview

Nine Men’s Morris is one of the oldest strategy games still played, and its board is deceptively small: 24 points on three nested squares joined by four spokes.

Each player has nine pieces. Line three up along a marked line — a mill — and you remove one of your opponent’s pieces. Reduce them to two, or leave them with no legal move, and you win.

The game runs through three distinct phases, and each one plays differently: placing all eighteen pieces, then sliding them along the lines, and finally flying once a player is down to three.

The board: 24 points, 16 mills

There are exactly 16 possible mills — four along each of the three squares, plus four along the connecting spokes. And here is the part worth knowing: every point on the board belongs to exactly two of them. No point is better than another for mill-building.

What does differ is mobility, and it differs a lot:

• Four points have four neighbours — the midpoints of the middle square, where the spokes meet.
• Eight points have three.
• Twelve points have only two — the corners of each square.

So the four middle-square midpoints are the strongest squares on the board. Not because they build more mills, but because a piece there can go four ways in the sliding phase, while a piece in a corner can go two. In a game you can lose simply by being unable to move, that is the difference.

Phase one: placing

Players alternate placing their nine pieces on any empty point. Pieces do not move yet.

Completing a mill during placement removes an enemy piece immediately, so the placing phase is not a quiet setup — it is where most captures happen. Every placement should either threaten a mill, block one, or claim a high-mobility point for the phase to come.

Mills and captures

Three of your pieces along one marked line is a mill. Close one and you remove one enemy piece.

There is a restriction: you must take a piece that is not itself in a mill — unless every enemy piece is in one, in which case anything goes.

That makes mills defensive as well as offensive. Pieces locked into mills are protected, so a player with several mills standing is hard to attack directly. It also means the threat matters as much as the mill: two pieces on a line with the third point empty forces your opponent to answer, and answering is a move they did not want to spend.

Phase two: sliding

Once all eighteen pieces are down, you move one piece per turn to an adjacent empty point along a line.

This is where the board’s geometry starts to bite. Pieces on two-neighbour corners are easy to seal in; pieces on the four-way midpoints stay useful. Empty points become scarce, and a player whose pieces are all boxed in loses without a single further capture.

The running mill

The strongest tactic in the game: a mill you can open and close repeatedly.

Set up two mills sharing a piece, or a mill with an empty point beside it, and you can slide one piece out and back again — closing the mill every second turn and taking a piece each time. Your opponent must find a way to occupy the point you keep returning to, and if they cannot, the game is effectively over.

The counter is to see it coming. Before your opponent breaks a mill, ask where that piece is going and whether it can come back. Taking the return point is usually more urgent than anything else on the board.

Phase three: flying

A player reduced to exactly three pieces may move to any empty point, not just an adjacent one.

That is a genuine reprieve. A player who was one capture from losing suddenly has the whole board available and can complete a mill from anywhere. Do not treat three pieces as a won game — the flying player often has more options than the one with six pieces stuck on corners.

You lose when you are down to two pieces, or when you have no legal move at all.

Strategy and tips

• Take the four-way midpoints early. Every point builds the same number of mills; only these keep you mobile later.
• Play threats, not mills. Two on a line with the third open forces a response, and forcing responses is how you get a free move.
• Build toward a running mill. One that reopens is worth more than two that just sit there.
• Block the return point. When they break a mill, the square they vacated is usually the one to take.
• Watch your own mobility. Being sealed in loses the game outright, no captures required.
• Do not relax at three. Flying can rebuild a mill from across the board.

Pass & Play and the computer opponent

Three AI levels, and they differ in kind. Easy and Medium play the tactics in front of them — completing their own mills and blocking yours. Hard searches ahead and weighs mobility, which is exactly the thing that decides the sliding phase. It will take a four-way point off you early and leave you shuffling corners.

Local Pass & Play hands one device between two people. Nothing is hidden, so the whole contest is reading the board.

Online multiplayer against a remote opponent is available in the Android and iOS apps. The browser version plays against the computer or a friend beside you.

Controls

• Placing: tap any empty point.
• Sliding: tap a piece, then tap a highlighted adjacent point.
• After a mill: tap the enemy piece you want to remove.
• Flying: at three pieces, tap a piece and then any empty point.

Three in a row gives you the capture. Choosing when and where that three-in-a-row appears — and making sure you can still move afterwards — is the real game.

If you liked Nine Men’s Morris

Checkers and Kōnane are the other capture-driven abstracts here — Kōnane in particular shares the idea that running out of moves is how you lose.

Disc Flip and Hex are the positional ones, where nothing is captured at all and the board itself is the contest.