This form of checkers is still played in Holland, and derives from the province Friesland. In Frisian draughts the objective is to capture all your opponent's pieces (draughts and wolves).

Pieces move by sliding diagonally forward to an adjacent empty square or by jumping over an enemy piece to a vacant square on the other side. Jumping over a piece captures it. Capturing is mandatory and you must keep jumping and capturing as long as it is possible. Draughts capture in all directions, also orthogonally, on squares of the same colour. They promote to wolves on the back row (the Frisian name for the King is "wolf"). Wolves may move forwards or backwards on the diagonals. They capture in all directions (also orthogonally, on squares of the same colour) and land anywhere behind the captured piece.

The wolf may only slide three times in a row. Then he must be set free by capture, or by the move of any other of the same player's pieces. This rule is not valid if the player has only wolves left. In endgames with two wolves against one, the stronger party must win in seven moves, otherwise it's declared a draw. Stalemate is a loss.

Frisian Draughts is similar to International Draughts. The main difference is that both men and wolves (kings) may capture orthogonally as well as diagonally. If you want to set up a position, even if the program is not likely to malfunction, the preferable method is to choose the "empty board" alternative.

Note! I have also implemented a simplified variant where one is not required to choose the line that captures the most pieces. However, capture with the wolf still takes precedence. This variant is played on the 8x8 board.