Sz'kwa

The same board is used by watermelon chess and one of the ancient Roman bear games.

[1][3] Players typically use gravel or dirt as the board and represent the pieces using shells, nuts, or pebbles.

[1] The author Clifford A. Pickover rated a "Hyperdimensional Sz'kwa" challenge as "extremely difficult".

Four semicircles form a north, south, east, and west arrangement in the interior of the larger circle.

Players drop one of their pieces on any vacant intersection point on the board.