Yin-Yang is a two player game of claiming territory. It is played on a checkered board with dark and light stones. The board starts with some stones on it, then players take turns moving and adding stones until no more moves are possible.
Player One tries to have stones on squares of matching color (dark on dark or light on light), and Player Two tries to have stones on squares of contrasting color (dark on light or light on dark). At the end of the game, count up each player's score. Player One scores one point for each stone that is on a square of the same color, and Player Two gets one point for each stone that is on a square of the opposite color. No one gets points for unoccupied squares.
The player with the higher score wins the game. If scores are tied, Player Two wins the game.
An entry into the About.com: 2004 Shared Pieces Game Design Competition.