The borders of the board are connected to build a torus. The setup was invented by Karl Fischer, perhaps in the 1970's, See "http://www.chessvariants.org/shape.dir/torus_standard_board.html".

The normal rules of chess are valid, the only exception beside the initial setup is that there is no castling.

Pawns promote as usual on the 8th (White) and 1st (Black) row. By 'Switch Piece Set' you can get a board image with highlighted promotion rows.

The graphic displays two views to the position from opposite points of the torus. You may move a piece at any part of the diagram, the zrf will synchronisize automaticly the other part.