The Rules of Cypher Chess
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III. The Cypher, or Spy.
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a. The Spy begins behind the Queen, at Court (d0 and d10).
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b. The Spy moves like a Queen.
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c. The Spy cannot be removed from the board, except in one case (see infiltration, below).
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d. No matter where the Spy is positioned, it cannot capture Field or Border pieces; however, when it is on the Border or at Court, it can check the King.
e. The Spy cannot block check in the Field or Border areas-- only within Court. In the Field and Border, the Spy is transparent to checking pieces. Nor can a Field or Border Spy block a flipping attack made by a Court Spy against a Court King from across the board.See discus-sion of flipping, below.
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f. Spies cannot attack each other, though they can block each other’s attacks on other pieces. (But see transparency exception, in e, above.)
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g. The Spy can check the opposing King from Court and Border squares and in the case of col-
lusion (see below).
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h. One square must stand between the Spy and either King and be-
tween the Spy and its counter Spy. For example, if the King is on a1, neither Spy can stand next to the King on squares z0, z1, z2, a0, a2, b1, b2 and b3. (See illus-trations.) If an opponent moves the Spy next to the other Spy or its own King, he or she loses the
game. See discussion of flipping, below.
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i.i. When an opponent moves the Spy onto the Field or Border from Court, he or she can also move a major piece onto a Court square (though doing so is optional). For notation purposes, this occurs as one move, but the Spy moves first, then the Field or Border piece moves second. Given this required sequence, the Spy must complete its move before the Field or Court piece can move to Court. In other words, the Spy cannot move to a Field square that is already occupied by the Court-bound piece and once the Spy has moved, the Court-bound piece cannot hop over it to reach its destination (un-less, of course, that piece is a knight). This sequen-tiality also impinges upon other options. For example, looking at move 32 of the sample game, one sees how White might have desired to free its Spy from the pin by moving it from Court and moving another piece, like the Rook, onto the back row. However, in this situation, the moment the Spy leaves Court the Black Spy flips the White King, thus ending the game.
i.ii. The Spy cannot trigger the entry of an additional piece until first re-entering Court, then exit-ing; however, major pieces already on Court squares can leave at anytime. Major pieces move into Court via their normal moves, e.g. a bishop enters on a diagonal, etc. (See Knight's moves.)
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j. Only the Spy can attack and capture pieces placed on Court squares. To launch an attack on a major piece that sits on a Court square, the Spy must do so from another Court square. If not al-ready on a Court square, it must re-enter Court as a separate move.
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k. The Spy, on a Court square, can attack a piece, also on a Court square, located on the other side of the board by crossing the Field (inclusive of the Border)--verti-cally, horizontally or diagonally--as long as there are no blocking pieces.