西瓜棋

The characteristics and gameplay of Watermelon Chess are as follows:
* The chessboard is circular, consisting of a concentric circle, four arcs and two intersecting lines.
* There are 21 chess points on the chessboard, and each side has six chess pieces, which are distinguished by color, red for the player and green for the opponent.
* During the game, the player and the opponent take turns to make a move each time. As long as either side surrounds the opponent's chess pieces and leaves the opponent's chess pieces with no way to go, they can eat the opponent's chess pieces.
* If the number of enemy chess pieces is reduced to two or less, the person can become the winner of the game.