3D Chess is a free online game in PopGameBox; it is played on a chessboard, a square board divided into 64 squares (eight-by-eight) of alternating color, which is similar to that used in draughts (checkers). 1. The king can move exactly one square horizontally, vertically, or diagonally. Only once per player, per game, is a king allowed to make a special move known as castling. 2. The rook moves any number of vacant squares vertically or horizontally. It also is moved while castling. 3. The bishop moves any number of vacant squares in any diagonal direction. 4. The queen can move any number of vacant squares diagonally, horizontally, or vertically. 5. The knight moves to the nearest square not on the same rank, file, or diagonal. Its move is not blocked by other pieces: it jumps to the new location. 6. A pawn can move forward one square, if that square is unoccupied. If it has not yet moved, each pawn has the option of moving two squares forward provided both squares in front of the pawn are unoccupied. A pawn cannot move backwards. They can capture an enemy piece on either of the two spaces adjacent to the space in front of them, but cannot move to these spaces if they are vacant.