Hollow Chess Makes the Board Part of the Match

Field notes

The rules alternate piece moves with board turns, displayed as W B✦ W B W✦ B W B✦. A player lifts an empty square and places it anywhere touching the board; the resulting hole blocks sliding pieces and can be used to escape an attack. The page also lists five bot levels, from Beginner through Brutal, plus correspondence play in which opponents exchange a new link after each move.