Hnefatafl the rules

The sides

24 attackers (dark) start on the edges. The king stands on the throne in the middle with 12 defenders (light). The attackers move first, then the players take turns.

Moving

Every piece, the king too, moves like a rook in chess: any number of empty squares across or down, never diagonally, never over other pieces.

Only the king may stop on the throne and on the four corners. Other pieces may pass over the empty throne.

Capturing

Trap an enemy piece between two of yours, across or down: it is captured. Only the moving player captures — you may safely move in between two enemies. A corner, and the empty throne, count as one of your pieces when trapping. The king helps his defenders capture.

The shieldwall

A row of two or more pieces along the edge is captured all at once when the enemy closes both ends of the row (a corner counts) and has a piece right in front of each of them. The king in such a row is not captured.

The king

The attackers capture the king by surrounding him on all four sides — or on three sides when he stands next to the throne, the throne being the fourth. The king cannot be captured on the edge of the board.

How the game ends

• Defenders win: the king reaches a corner, or builds an edge fort — he stands on the edge, can move, and is walled in by defenders the attackers can never capture.
• Attackers win: they capture the king, or surround all the defenders so that none of them can reach the edge.
• A player who cannot move loses. If the same position comes up a third time, the defenders lose — so the king cannot just walk back and forth.

Playing here

• Click a piece, then one of the dots. Arrow keys and Enter work too.
• Choose to play the attackers or the defenders when you start.
• Resign gives your opponent the win; End game stops the game without a winner.
• Logged in with Discord, a win against the computer unlocks rewards: Easy — piece colours, Medium — 3D pieces, Hard — a crown on your HAKOO avatar.