Abyss

This game is played on a 5×5 board. One player drops 6 white stones and 6 black stones on empty cells. The other player then may: (a) choose a color and be the second to move, or (b) choose to move first and the other choose color. On each turn, each player must orthogonally slide a friendly stone, pushing all stones it that line, until at least one enemy stone is pushed out of the board. When one player cannot execute a valid move, the game ends. The player with more stones on the board wins.