Halatafl, like Hnefatafl, is a Viking board game. The similarity, however, pretty much stops right there. Actually, the name has been applied to two board games; one resembles the game of Checkers with a few complications, while the other can be found under the name Fox and Geese.
The original rules to Halatafl are not known for sure, and there were probably many variations, but what follows is the reconstruction that I happen to know. Halatafl is played on a seven by seven board with the center and four corner squares left empty. The blank board is drawn with those five squares marked off and diagonals drawn across the board as follows:
---------------
| _| |_ |
| \ / |
| \ - / |
| | | |
| / - \ |
| _ / \ _ |
| | | |
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Each player begins with twenty two pieces on the board, arranged thusly:
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| # 0 0 0 X X # |
| 0 0 0 0 X X X |
| 0 0 0 0 X X X |
| 0 0 0 # X X X |
| 0 0 0 X X X X |
| 0 0 0 X X X X |
| # 0 0 X X X # |
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Pieces can either move one space at a time orthogonally sideways or forward (towards the enemy), or diagonally along the drawn lines only, but not backwards (towards one's own side), or they can jump over another piece to an empty space behind it. Jumps can be made in any direction, as many times as possible in one move, and you can jump over both your own and enemy pieces. As in Checkers, jumping over an enemy piece removes it from the board. The corner squares can be used as intermediates during a series of jumps, but no piece can remain there.
Play begins with 0 (white) moving a piece into the center square, after which X (red or black) jumps it. Play proceeds until one side loses by having fewer than five pieces remaining on the board.