The letters "JW" stand for Jeff Weeks, a mathematician who proposed this chess variant on a torus board in the early 1980's for use in his book "The Shape of Space". Later he also created computer programs for this and other games on such surfaces. You may look for them to "http://www.geometrygames.org/TorusGames/".

The chessboard becomes a torus when you first connect two opposite borders to build a cylinder and then curve this cylinder so that you can glue its free circular edges. On a torus do not exist neither edges nor corners, each point could be chosen as center of your focus.

To better imagine the moves on this unbounded surface with the zrf two views are displayed. They show the same position from opposite points. In all variants except in the last you may move a piece in any of the two parts of the diagram, the zrf will syncronisize automatically the other part.

Most pieces and their moves and the objectives of the game are the same as those of standard chess, "null moves" (once around the board to the same field) are not allowed.

Only the rules for Pawns are altered: With respect to the 90∞ rotational symmetry of the torus they move one step orthogonal in all four directions and capture diagonal also in four directions.

In the chessvariant context this piece also is known as "Steward", and therefore I used the special image for it, but with the "Switch Piece Set" feature of Zillions you may change it to the usual picture for the pawn.

There are 8 variants. The default variant shows the original setup by Jeff Weeks (9 pieces per player). The four next Variants have different setups by me (Alfred Pfeiffer) with more pieces per player. In a further variant a setup is used that was referred by Charles Gilman on the chessvariants.org site. The remaining two variants are made for experimental purposes.