How to play Mill

Mill, best known as Nine Men's Morris, is a classic board game for two players. Each side starts with a handful of stones and takes turns putting them on the points of a board drawn as nested squares. Three of your stones in a straight line make a mill, and every mill lets you take one of your opponent's stones. Bring your rival down to two stones, or leave them with no move, and you win.

The game has been played across Europe for many centuries. There is no luck, and the game has two halves: first you fight for good points while placing stones, then you manoeuvre them along the lines, opening and closing mills while blocking your opponent's. You play the white stones against the computer.

How to play on skill.games

In the settings popup choose a difficulty (Easy, Normal, Hard or Crazy) and a Board: 6 men, 9 men (the classic game, selected by default) or 12 men. Press PLAY. You always place the first stone.

• Placing: while you still have stones in hand (lined up next to the board), the status reads PLACE A STONE. Tap any empty point.
• Moving: once all stones are placed, tap one of your stones to select it, then tap a green-marked free point next to it. When you are down to three stones on the 9 or 12 men board, the status reads FLY TO ANY POINT and you may move to any empty point.
• Taking a stone: when you close a mill, the status reads MILL! TAKE A STONE and the stones you are allowed to take are ringed in red. Tap one to remove it.
• Score line: the top of the screen shows how many stones each side has left, counting stones still in hand. Once the moving phase starts, a "No mill" counter shows how close the game is to the 50-turn draw.

The menu button in the top-left corner pauses the game, with options to resume, start a new game or turn the sound off. The game is saved at the start of every turn, so you can CONTINUE an unfinished match next time.

At the end, the results screen shows the stones left on each side, the stones you took and lost, the number of turns and how the game ended, together with your statistics: wins, losses, draws, win rate, current streak and best streak. Each board keeps its own record per difficulty.

Rules

The board. The points are the corners and middles of the squares, joined by lines. Each player has the same number of stones: 6, 9 or 12 depending on the board. The board starts empty.

Phase 1: placing. Starting with you, the players take turns putting one stone from their hand on any empty point.

Phase 2: moving. When both players have placed all their stones, each turn you slide one of your stones along a line to a neighbouring empty point.

Flying. On the 9 and 12 men boards, a player who is down to exactly three stones may move a stone to any empty point on the board, not just a neighbouring one. There is no flying on the 6 men board.

Mills. Whenever your move or placement creates three of your stones in a row along a line, you have formed a mill and you take one of your opponent's stones off the board.

• You may not take a stone that is part of a mill, unless every one of your opponent's stones is in a mill.
• Each move that closes a mill takes one stone. A mill that stays on the board does not keep taking stones, but you can open it by moving a stone out and then close it again on a later turn to take another.
• Captured stones never come back.

Winning. You win when your opponent has fewer than three stones left (on the board and in hand together), or when it is their turn and they have no legal move.

Draws:

• 50 turns in a row in the moving phase (yours and the computer's together) without anyone closing a mill;
• on the 12 men board, if all 24 points fill up so that nobody can move.

Strategy tips

• Don't rush to make mills while placing. A quick mill early on often leaves your stones scattered and easy to block. Points where several lines cross, such as the middles of the sides on the middle square, give you the most options later.
• Keep your stones mobile. In the moving phase, a player with no legal move loses. Avoid packing your stones into corners where they can be blocked, and look for chances to hem the computer in.
• Block two-in-a-rows. Whenever the computer has two stones on a line with the third point empty, check whether it can reach that point on its next turn, and fill it first if so.
• Build a running mill. The strongest formation is a stone that can slide back and forth between two mills, closing one every turn. Once you have one, it is very hard to stop.
• Take the right stone. When you capture, remove a stone that is about to complete a mill, or one that would free a blocked group, rather than any stone at random.
• Know the endgame. With three stones left on the 9 or 12 men board, your stones can fly, which makes them dangerous. Before you take the opponent down to three, make sure you are not leaving two open lines that a flying stone could complete.

Difficulty levels

• Easy: considers only its own next move and plays a random move about four times in ten, though it still takes a stone when it has a mill. It sometimes lets you form a mill.
• Normal: looks at its move and your reply, and plays a random move about one time in seven.
• Hard: looks several moves ahead and almost never plays a careless move.
• Crazy: looks the furthest ahead and never plays at random. The toughest opponent.

Modes

The Board setting picks the size of the game:

• 6 men: a smaller board of two squares, six stones each. A short game, and there is no flying.
• 9 men: the classic Nine Men's Morris on three squares, with nine stones each and flying at three stones.
• 12 men: the three squares are also joined at the corners by diagonal lines, so mills can run diagonally too. With twelve stones each and only 24 points, the board can fill up completely during placing, which ends the game as a draw.