Copenhagen hnefatafl rules

The game in short

Eleven squares by eleven. A large attacking army around the rim against a small defending force at the centre with a king. The attackers want the king; the defenders want a corner. The attackers move first.

What separates Copenhagen from the plainer codes is the ending. Three additional results — a shieldwall sweep, an edge fort and full encirclement — mean that a decisive grip on the position counts as a win, instead of dragging on until the move limit.

Setting up

Files run a to k from left to right, ranks 1 to 11 from the attackers’ side. The throne is f6 and the corners are a1, k1, a11 and k11.

Twenty-four attackers stand in four groups of five along the middle of each edge, each group with one man stepped forward in front of it.

• South: d1, e1, f1, g1, h1, with f2 in front.
• North: d11, e11, f11, g11, h11, with f10 in front.
• West: a4, a5, a6, a7, a8, with b6 in front.
• East: k4, k5, k6, k7, k8, with j6 in front.

Twelve defenders stand in a cross around the king, who begins on the throne at f6: f4; e5, f5, g5; d6, e6, g6, h6; e7, f7, g7; f8.

Movement

Every piece, king included, slides along a rank or a file any number of empty squares and stops on an empty square, exactly like a rook. No diagonal moves, no jumping and no capture by landing on a piece.

Only the king may end a move on the throne or in a corner. Any piece may slide straight across the throne once the king has left it, but may not stop there.

Capture

Capture is custodial and active. Move a piece so that an enemy soldier is caught between it and another of your pieces, along a rank or a file, and the enemy soldier is removed. The trap only works if you complete it by moving: a piece that walks into a gap between two enemies is not captured.

One move may capture on two or three sides at once. Check all four neighbours of the square you land on.

Hostile squares stand in for the second piece. Each empty corner is hostile to both sides. The throne is hostile to both sides while it is empty. While the king is sitting on it, the throne is hostile to the attackers only, so a defender may pin an attacker against the occupied throne but an attacker may not pin a defender against it.

The king is armed: he counts as a defender when a capture is being made, and attackers can be taken between the king and one of his men.

Winning

The defenders win in any of these three ways.

• Escape. The king reaches any one of the four corner squares.
• Edge fort. The king stands on a square on the edge of the board, walled in by his own men in a formation the attackers cannot break — no defender in the wall can be captured — and the king still has at least one empty square to move to inside it. The position is a win at once; the defenders do not have to demonstrate it move by move.
• No moves. The attackers have no legal move at the start of their turn.

The attackers win in any of these four ways.

• Capture the king. All four squares orthogonally next to him must be held by attackers, or be hostile squares. A king standing on the edge of the board has only three neighbours on the board and therefore cannot be captured there.
• Shieldwall. A row of defenders standing along an edge is swept off together. Each defender in the row must have an attacker directly beside it on the inward side, and the row must be closed at both ends by an attacker or by a corner square; the move that closes the last end makes the capture, and the whole row comes off. A shieldwall against the defenders wins the game outright here.
• Encirclement. The attackers form an unbroken ring so that no defender at all, king included, can reach any square on the edge of the board.
• No moves. The defenders have no legal move at the start of their turn.

Repetition and the move limit

• A player who is about to repeat the same position for the third time must play something else instead. If they will not, or cannot, they lose the game.
• If a hundred moves pass without progress, the game is drawn.

Sources

Everything on this page is written from scratch. These are the works it leans on, and what each one settles.

• The Copenhagen hnefatafl code

  The tournament rule set agreed by the Copenhagen hnefatafl group. It fixes everything on this page, in particular the three extra endings and the rule that the occupied throne is hostile to attackers only.