# Spherical chess

invented by Don Miller in 1965 - modified by Leo Nadvorney in 1972

### Rules

The Laws of Chess apply, except as follows:

1. The board is spherical:
2. c7 d7 e7 f7 g7 h7 a7 b7 c7 d7 e7 f7
c8 d8 e8 f8 g8 h8 a8 b8 c8 d8 e8 f8
g8 h8 a8 b8 c8 d8 e8 f8 g8 h8 a8 b8
g7 h7 a7 b7 c7 d7 e7 f7 g7 h7 a7 b7
g6 h6 a6 b6 c6 d6 e6 f6 g6 h6 a6 b6
g5 h5 a5 b5 c5 d5 e5 f5 g5 h5 a5 b5
g4 h4 a4 b4 c4 d4 e4 f4 g4 h4 a4 b4
g3 h3 a3 b3 c3 d3 e3 f3 g3 h3 a3 b3
g2 h2 a2 b2 c2 d2 e2 f2 g2 h2 a2 b2
g1 h1 a1 b1 c1 d1 e1 f1 g1 h1 a1 b1
c1 d1 e1 f1 g1 h1 a1 b1 c1 d1 e1 f1
c2 d2 e2 f2 g2 h2 a2 b2 c2 d2 e2 f2
3. A rook moving through a pole emerges on the opposite side and continues in a straight line, as for example Ra3-a1-e1-e4.
4. Bishop moving through the pole from a given square emerges one square away from the diametrically opposite one, depending on which direction it is moving. Examples are Bh3-g2-f1-a1-h2-g3 and Bd3-e2-f1-c1-d2-e3, but not Bh3-g2-f1-c1.
5. Moves of other pieces can be inferred from the above; for example, a knight move can be regarded as a 1-step R move followed by a 1-step B move, such as Sd1-h1-g2/a2.
6. Since are no edges, pieces can move around the board along the ranks as in Cylindrical Chess.
This requires two ruling like those for Cylindrical Chess:
1. A piece may not make a move around the board (like Rh3-a3-h3) that leaves the position unchanged, nor may it make an infinite (never ending) move.
2. Two new forms of castling are possible, if the usual condition are fulfilled: Ka1-c1, Rh1-d1 over a1 (written C0-0-0) and Ke1-g1, Ra1-f1 over h1 (written C0-0).

### Notation

On transpolar moves it may make things clearer to indicate the square from which the pole was crossed, but this is not necessary.