Ard ri is the scottish version of tafl game which was played by vikings.
The king is place in the center of the board, his eight defenders are placed around him, the sixteen attackers are placed on each side of the board, one in front of three others.
The king player must bring the king to one corner of the board, the attacker must capture the king.
The pieces move orthogonally with no limit distance, attackers and defenders are taken when two opponents are on opposite sides around him (never in diagonals) King is taken when he is surrounded by four attackers.
Sorry for my bad english, you can check for variants on the web.