(1) each of the two matches is a piece of chess.
(2) empty board opening.
(3) black first, white, then alternate, only one son at a time.
(4) the chess pieces are placed at the blank points of the chessboard, and the pieces are not allowed to move to other points after being laid down. They must not be removed from the chessboard or picked up elsewhere.
(5) the first black pawn on the chessboard can be arbitrary point of intersection.
(6) it is the right of both parties to take turns, but allows either party to give up the right (PASS right).