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Hnefatafl (Ner-far-taff-all) is a Tafl Game, though it is a lost art in the modern day. The aim of the game is either to capture the king, or get the king to a corner depending on which side you are playing on.

It is played on an 11 x 11 board:

Board

Although this and the layout are the only rules that has survived to this day, another Tafl game, Tablut, had its rules recorded and it is assumed that the rules where the same except for board and layout.

The layout is as follows:

enter image description here

The rules and pieces are as follows:

  • Moves are taken in turns

  • The king (white with cross) starts on the Konakis, the central square

  • The Konakis can not be occupied by any other piece apart from the king

  • Once the king has left the Konakis he can not return to it

  • The 12 Swedes (white) or defenders surround the Konakis in a diamond formation

  • The 24 Muscovites (black) or attackers start in groups of 6 with one facing towards the Konakis

  • All remaining squares can be occupied at any point during the game by any piece

  • All pieces can move vertically or horizontally, but not diagonally, for as many squares as the player chooses, unless blocked by the opposition or reaching the edge of the board (medieval Rook)

  • Pieces can't 'jump' over another piece, they will be blocked

  • If the king has an unimpeded path to a corner (if there at no pieces inbetween the king and the corner, and the move is legal) and isn't blocked by a Muscovite, he may escape and white has won the game.

  • If the king has a path to a corner, he must say 'raichi' (check) to alert his opponent. If he doesn't say this and escapes then it is an illegal move.

  • If the king has multiple paths to corners and hence an inevitable victory, he must say 'tuichu' (checkmate)

  • Any piece (except the king) can be captured and removed from the board if it is surrounded on two opposite sides by the opposing team

  • If the king is surrounded on 4 sides by the Muscovites he is taken capture and blacks win. If he is only surrounded on 3 sides he can escape

  • If the king is surrounded on 3 sides, and the 4th side is blocked by the Konakis he is taken capture

What is the minimum moves that the king can be escape in and what is the minimum moves that the Muscovites can capture him in?

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  • $\begingroup$ Can you clarify piece movement? Can each piece move only one square or multiple? What exactly do you mean by "having a path to a corner"? $\endgroup$ – greenturtle3141 Oct 11 '16 at 18:37
  • $\begingroup$ @greenturtle3141, I'll clarify. The pieces are basically rooks from chess. Path to a corner means no piece is inbetween the king and the corner and the move is legal $\endgroup$ – Beastly Gerbil Oct 11 '16 at 18:49
  • $\begingroup$ I see now. I wonder if it's possible for the swedes to create a fortress and force a draw. $\endgroup$ – greenturtle3141 Oct 11 '16 at 18:51
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    $\begingroup$ This seems excessively difficult. So far as I know, the game hasn't been solved; it feels to me at least as difficult as checkers, which has been solved in the sense that the outcome (from the initial position) with best play is known but not (I believe) in the sense of always finding minimal winning moves when a win exists. Solving checkers was a big job. Is there any reason to think that answering this question is feasible? $\endgroup$ – Gareth McCaughan Oct 11 '16 at 22:11
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    $\begingroup$ Are we assuming both players are playing optimally, or are they colluding to try to get to the minimum? If the players cooperate, it seems like the king can escape in a minimum of 6 moves, but if black is working to stop him, it seems unlikely that that could happen. $\endgroup$ – GentlePurpleRain Oct 12 '16 at 21:04
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(Thanks to gtwebb for pointing out these solutions)

White can win in

five moves:

1. W: h6 $\rightarrow$ h10 $\quad$ B: h1 $\rightarrow$ h9
2. W: g6 $\rightarrow$ i6 $\quad$ B: k8 $\rightarrow$ k10
3. W: f6 $\rightarrow$ h6 $\quad$ B: k7 $\rightarrow$ k9
4. W: h6 $\rightarrow$ h1 $\quad$ B: k6 $\rightarrow$ k8
5. W: h1 $\rightarrow$ k1 $\quad$ WIN! Animation of win for White

Black can win in

three moves:
1. W: f4 $\rightarrow$ j4 $\quad$ B: e1 $\rightarrow$ e3
2. W: f5 $\rightarrow$ f3 $\quad$ B: g1 $\rightarrow$ g3
3. W: f6 $\rightarrow$ f3 $\quad$ B: a4 $\rightarrow$ f4
Animation of win for Black

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  • $\begingroup$ Love the animations, well done $\endgroup$ – Beastly Gerbil Oct 13 '16 at 18:09
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I would say it takes 6 moves for the white to win in the best case, get 3 white out of the way, then take 3 moves to get the king to a corner, while the opponent do stupid things that hinders you in no way.

EDIT

And I think it would take 5 moves in the best case for the black to win. It would take 5 turns for the white to remove the top 4 pieces that are in the way and send the king 1 square up and during he do that send 3 black pieces to corner him 1 with the x at his back.

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    $\begingroup$ I think you could have a black win in less moves. White bottom piece (f4) out of the way (j4). Black e1 upto e3. White f5 to f3. Black g1 to g3 for capture. King to f3. Black a4 to f4 for the win. I think white could win in 5 as well. Only need to get 2 whites out of the way. $\endgroup$ – gtwebb Oct 13 '16 at 3:18

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