Blackstone

Blackstone is a two-player game played on a square board of any even size, of side length 6 or longer. The perimeter cells are initially populated with red and blue stones. Mark Steere designed Blackstone in March 2024. Alek Erickson made a material contribution to the design of Blackstone. Play The two players, Red and Blue, take turns making a non-capturing Chess queen move with a stone of their own color, starting with Red. [That is, move your stone any number of squares along a straight, unobstructed path, horizontally, vertically, or diagonally.] Immediately after moving, place a neutral, black stone on the square you moved from. After you move your stone and place a black stone, if any red or blue stones are surrounded by adjacent stones of any of the three colors, and are completely blocked from moving, remove all of the red and blue stones so blocked, concluding your turn. Blackstone is a game of annihilation. If your move kills all remaining stones of only one color (red or blue), that color player loses. If your move kills all remaining red and blue stones, you win. Variants Medium churn: If your move completely blocks any red or blue stones (as described above), remove those stones and all of the black stones that contributed to the kills from the board, concluding your turn. High churn: If your move completely blocks any red or blue stones, remove those stones and ALL of the black stones from the board, concluding your turn.