Nine Men’s Morris against the computer

Nine Men’s Morris: place your nine pieces, form mills of three in a row and take your opponent’s pieces. Whoever is reduced to two pieces, or cannot move any more, loses.

Source: Wikipedia: Mühle (Spiel) – placing, moving and endgame phases, capture rule (tournament rule 2010), solved as a draw (Gasser). Updated: 28 September 2026.

How it is calculated

How to play nine men’s morris

The board consists of three nested squares joined at the middle of each side – 24 points in total. Each player has nine pieces; White moves first. The game has three phases:

Placing: players take turns placing a piece on an empty point until all nine are on the board.
Moving: each turn you slide one piece along a line to an adjacent empty point. A player who cannot move loses.
Flying: once a player is down to three pieces, they may move a piece to any empty point. You can switch this rule off above the board.

Three of your pieces in a line form a mill. Whenever you form a mill, you remove one of your opponent’s pieces – but not one that is part of a mill, unless all of their pieces are in mills. A player reduced to two pieces loses.

Controls

In the placing phase simply tap an empty point.
In the moving phase tap one of your pieces (green ring if it can move), then a green target point.
After a mill, the pieces you may take are marked in red.

The three computer levels

Easy: looks one move ahead and often plays at random.
Medium: searches three plies and weighs pieces, open mills and mobility.
Hard: iterative alpha-beta search up to eight plies, capped at about 0.7 seconds per move.

Tips and background

During placing, prefer the junctions in the middle of the sides over the corners – they offer the most moves.
A double mill (running mill) lets you open and close a mill every turn and usually decides the game.
Nine men’s morris is solved: with perfect play from both sides it is a draw (Ralph Gasser, ETH Zurich, 1993/1996).

Honest limits

Here a game is drawn after a threefold repetition of the same position or after 50 moves without a capture – our own simplification; official tournament rules may differ. The computer uses no opening book or endgame database, so it can be beaten.

Storage and privacy

Settings and your record against the computer are kept in your browser’s localStorage (key muehle). Nothing is sent to a server.

More board games: checkers, chess against the computer and four in a row.

Frequently asked questions

What are the rules of nine men’s morris?

Players first place nine pieces each in turn, then move them to adjacent empty points. Three in a line is a mill and lets you remove an opposing piece. A player with only two pieces left, or with no legal move, loses.

Can pieces fly in nine men’s morris?

Under the common rules, yes: a player with only three pieces left may move to any empty point. You can switch this rule off here.

Can you remove a piece from a mill?

Normally not. Only when all of the opponent’s pieces are in mills may one of them be taken.

Is nine men’s morris a solved game?

Yes. Ralph Gasser showed in the 1990s that perfect play by both sides leads to a draw. The computer here does not play perfectly, so you can beat it.

What is the best strategy in nine men’s morris?

Keep your pieces mobile, occupy the junction points early, block your opponent’s open mills and aim for a double mill that you can open and close every turn.

Sources and legal basis

As of: 28 September 2026 · Editorial policy