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This page is written by the game's inventor, Charles Gilman.

Quadruple Besiege Chess

Köksal Karakus' Besiege Chess takes 2 FIDE arrays, changes one lot's Kings to third Queens, and joins the Black camps back to back. His Torus Chess extends this to wrap round, with White camps joined as well and second Kings changed instead to Queen+Knight compounds. That can be considered a double besiege variant. Other variants such as Ralph Betza's Doublewide Chess join boards file to file, with no siege element but 16-Pawn front ranks. This too can be done twice over to wrap around. Each such variant can be played with two FIDE sets with a King aside marked. More complex rearrangements include one board splitting the middle of another as in David Short's Double Chess (third Queens again replacing outer Kings) and my suggested 4-player form of Christopher Hodde's Seachess (with fully distinguishable sets).

The boards connect along all four edges. The rule is that each board's top edge connects with the other's bottom edge, and each board's left edge to the other's right edge. This makes every orthogonal loop round after 16 cells and every diagonal after 8 - notably the long diagonals of each board which lead straight back on themselves. Camps are in the middle of each board, besieging each other from all sides.

There is no connection to the Besieger promotee in my 3d Shogi variant Tunnelshogi, a Unicorn promoted by adding the Wazir move and so unavailable on square-cell boarss.

I have since added pages appying this to 9-file variants for single sets on 2 7x7 boards and double sets on 2 9x9 boards as well as 10-file and hex variants. My Twin-board subvariants of Ecumenical Chess also include a Quadruple Besiege one, included there as it has a wider range of pieces than most QB variants.

Setup

BASIC QB CHESS

KNIGHTED-PIECE QB CHESS

WILDEURASIAN QB CHESS

MIXED-ERA QB CHESS (half FIDE, half Chaturanga)

COURIER QB CHESS (filled out with duplicate short-range pieces)

MITRE QB CHESS (promotion and reintroduction as QB on 98 and 162 squares)

ECUMENICAL QB CHESS

The diagrams show one of the four joins. The thing to remember is that left and right wrap round to each other, but the top-bottom wrap is skewed, so that the left half of the top continues to the right half of the bottom and vice versa. Here are examples for the first two arrays with a top-bottom join shown:

BASIC QB CHESS

KNIGHTED-PIECE QB CHESS

WILDEURASIAN QB CHESS

MIXED-ERA QB CHESS (half FIDE, half Chaturanga)

COURIER QB CHESS (filled out with duplicate short-range pieces)

In these diagrams it is the top-bottom wraparound that is straight and the left-right one that is skewed.

Somewhat diminishing the distinction between ranks and files is the fact that what are ranks to half the Pawns are files to the rest. Also, any two non-parallel orthogonals intersect twice, once on each board. Perhaps one group should be lettered A-H, the other I-P, and the whole FIDE boards 1 and 2.

Pieces

All pieces have extrapolations of their FIDE moves, but as only one of the four joins can be represented physically some guidance might be useful.
The PAWN moves one cell orthogonally except when capturing, which it does one cell diagonally. Pawns start moving toward the nearest join, and can never reach or cross their own long diagonals unpromoted. On crossing the join they move away from the nearest join. They can capture across an enemy long diagonal in either direction, including reversing a previous move if an enemy moves to the vacated cell. A Pawn actually on an enemy long diagonal may make a noncapturing move away from either nearest join, but capture only inward along the long diagonal. There are sixteen Pawns aside.
The ROOK moves up to 15 steps orthogonally through empty cells. Unblocked, or blocked by only one piece per orthogonal, it can reach any cell on the orthogonals where it starts on both FIDE boards, including the intersection on the other board but not a null move to the cell where it starts. It is blocked from entering the other board from above/below/the left/the right by any piece below/above/right of/left of itself on its own board. It takes at least two pieces to block a Rook from a cell completely, four to block it from the other intersection. There are four Rooks aside.
The BISHOP moves up to 7 steps diagonally through empty cells. Using any one join and imagining the opposite one, any diagonal can be easily visualised as 8 cells of the same colour in a line, like a FIDE long diagonal, each diagonal then wrapping round on itself (not, as might be expected, on the one furthest from it). Unblocked, or blocked by only one piece per diagonal, it can reach any cell on the diagonals where it starts, except a null move to the cell where it starts. It takes at least two pieces to block a Bishop from a cell completely, four to block it from the other intersection. There are four Bishops aside.
The KNIGHT makes a 2:1 leap, which in this geometry is the same as a 7:6, 9:6, 10:7, 14:1, or 15:2 leap. Any leap that is visibly one of these on a board with one join is valid. Nothing can block a Knight, not even a piece on the 3:2 and 6:4 stages of a 9:6 leap! Note that 6:1, 7:2, 9:2, 10:1, 14:7, and 15:6 are not valid Knight moves. There are four Knights aside.
The QUEEN combines the Rook and Bishop as described above. Likewise the MARSHAL combines Rook and Knight and the CARDINAL Bishop and Knight. Each player has three Queens in the basic variant, and one of each compound in the Knighted-piece variant.
Wildeurasian QB adds in the CAMEL which makes a 3:1 leap - in this geometry the same as 7:5, 9:5, 11:7, 13:1, or 15:3 (but not 5:1, 7:3, 9:3, 11:1, or 15:5), and the GNU which is the triagulating compound of Knight and Camel.
The It also adds in the pieces CANNON/ARROW/TANK. These differ from the Rook/Bishop/Queen respectively in that capturing requires exactly one intervening piece, which may be of either army and is not itself captured. Mixed-Era, Courier, and Mitre QB Chess add further pieces.
The KING moves one cell orthogonally or diagonally, including between the top and bottom or left and right edges of opposite boards or between opposite corners of the same FIDE board. On two boards with one physical join this can be envisaged as 1:0, 1:1, 7:7, 8:7, 15:0, and 15:1 leaps - but not 7:0, 8:0, 7:1, 8:1, or 15:7. There is one King aside.

Rules

There is no initial double-step move, En Passant, or Castling.

Pawns reaching a board's innermost 16 cells are promoted to any other capturable array piece.

Checkmate and Stalemate are as in FIDE Chess.


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By Charles Gilman.
Web page created: 2006-02-05. Web page last updated: 2016-03-21