Hnefatafl
Fetlar Hnefatafl, as published by the Fetlar Hnefatafl Panel in 2008. Two sides share an 11×11 board and want different things. The attackers move first and try to surround the King. The defenders try to escort him onto a corner.
This is the armed-king game. The King captures the same way any other piece does. Shieldwall, edge forts, and encirclement are not part of these rules.
The board
Files run a to k from left to right. Ranks run 1 to 11 from bottom to top, so the centre is f6.
a b c d e f g h i j k
11 # . . A A A A A . . # 11
10 . . . . . A . . . . . 10
9 . . . . . . . . . . . 9
8 A . . . . D . . . . A 8
7 A . . . D D D . . . A 7
6 A A . D D K D D . A A 6
5 A . . . D D D . . . A 5
4 A . . . . D . . . . A 4
3 . . . . . . . . . . . 3
2 . . . . . A . . . . . 2
1 # . . A A A A A . . # 1
a b c d e f g h i j k
A is an attacker, D a defender, K the King. # marks a corner refuge. The centre f6 is the throne.
There are 24 attackers, 12 defenders, and the King. The attackers are the dark pieces (player 1) and move first. The defenders and the King are the light pieces (player 2).
The throne and the four corners are restricted. Only the King may stop on them. Every other piece may slide across the empty throne, and must not finish there.
A turn
Players alternate. A turn is one slide of one of your own pieces.
A piece slides any number of empty squares orthogonally, like a rook, and may not jump. It stops on an empty square. A diagonal step is not a move. Passing is not a move: a side that has no slide has lost.
Custodial capture
After a piece lands, it may capture in any of the four orthogonal directions, and in more than one of them on the same move.
An ordinary piece — anything except the King — is captured when it is sandwiched: your piece on one side, and a hostile square on the other. The hostile square is:
•
any piece of the side that just moved, including the armed King
•
a corner, whether or not anyone stands on it
•
the throne, but only while it is empty
before after
. D A . . . A .
A . . . → A A . .
The attacker stepped up beside the defender. The defender's other side was already an attacker, so the defender is taken. A piece that walks into a sandwich is safe: only the side that just moved captures, and only outward from the square it landed on.
The King on the throne is an anvil for the defenders and not for the attackers. While he stands there, a defender can capture an attacker against him, and an attacker cannot capture a defender against him. Once he leaves, the empty throne is hostile to both sides.
The King himself is never taken by this sandwich.
Capturing the King
The attackers win by surrounding the King, and only when it is their move that completes the surround.
The King must be off the edge. Every orthogonal neighbour must then be held, by an attacker or by the throne square itself. The throne counts even when it is empty. A bare two-sided sandwich does not take him, and he is never taken while he stands on the outer frame, corners included.
Four attackers, off the edge:
Three attackers and the throne. Here T is the throne, and the King has stepped off it:
Four attackers close the same shape when the King is still on the throne. The throne is not one of the four sides in that case, because he is standing on it.
How the game ends
•
The defenders win the moment the King stops on a corner. That arrival is settled before any capture, so a piece that would have been taken by the landing is left where it stands.
•
The attackers win the moment their move surrounds the King, as above. He is taken off the board.
•
A side that has no legal slide loses. The other side wins. The King may still be on the board; this is not a capture.
•
The same arrangement of pieces, with the same side to move, is a draw the third time it occurs. The draw is immediate. The opening counts as the first time that position has occurred with the attackers to move.
There is no repetition warning before the move that draws the game. The platform records the draw and writes the reason into the log.