The board can be imagined as a cylinder with no horizontal edges on either side.
The board can be imagined as being wrapped around a cylinder resulting in a board with no horizontal edges. Therefore, the H file sits next to the A file, and pieces can move freely (and give check) from side of the board to he other.
Pieces can even capture and mate around the cylinder too. Note the pawn capture from H to A. Also that the Rook at C2 can capture both black Pawns at E2 and F2 - one from each direction!
Pieces can not return to their starting position, which would effectively be not moving at all!Pawn promotion rules remains the same as Standard ChessNormal Standard ChessEn passant rules remains the same as Standard ChessCheck and Checkmate rules remain the same as Standard ChessStalemate conditions remain the same as Standard ChessDraw conditions remain the same as Standard ChessWinning conditions remain the same as Standard Chess