Rules for 3-D Chess

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# Rules for Tri-Dimensional Chess

## Preface

These rules are intended for the private use of visitors to this website. Reproducing these rules in any manner whatsoever for the purposes of obtaining a profit is expressly prohibited.

These rules are not intended to cover all possible situations that may arise during a game. Where cases are not precisely addressed by any Section contained herein, it should be possible to reach a correct decision by studying analogous situations that are presented.

In the Sections that follow, "he", "him" and "his" can be substituted with "she", "her" and "hers," respectively.

## Section 1: The Chessboard

```The game of chess is played between two opponents by moving pieces on a
series of square boards collectively referred to as a "chessboard".

1.1  The chessboard is composed of 64 equal squares (the same number of
squares found on a conventional chessboard), with alternating light
("white") and dark ("black") squares.  These squares are divided among
seven individual boards, three of which are at fixed positions and
four are movable.

1.2  The three fixed boards are four squares by four squares and are
permanently affixed to a stand so that the boards are arranged in a
stair-step fashion with a common vertical distance between each level
and each level offset by two ranks of squares.

1.3  The lowest fixed level is called White's Board.

1.4  The middle level is called the Neutral Board.

1.5  The top level is called Black's Board.

1.6  Each fixed board has two pins at each corner of the board, one
projecting upward from the top surface of the board and one
projecting downward from the bottom surface. These pins are used to
attach the remaining four boards (generally referred to as attack
boards) to the fixed boards.

1.7  Each attack board is two squares by two squares and is mounted on
a post equal in length to 1/2 the distance between the fixed levels,
minus 1/2 the thickness of the attack board. Individual attack boards
are named according to their starting position (see Section 1.8 and
2.1).

1.8  The starting positions of the attack boards are on pins located at
the outermost corners of the upper and lower level with White's
attack boards below White's Board, and Black's attack boards above
Black's Board. When an attack board is placed on any given pin, one
square on the attack board will be directly over or under a corner
square of the fixed level to which it is attached. The attack board
must always be oriented so that the color of this square matches the
color of the square it overlaps.

1.9  Each player has limited control over the movement of the two attack
boards that begin the game on his side of the chessboard (see
Section 5.1 and Section 7).

1.10 The chessboard is placed between the players in such a way that
the near corner to the right of each player is light ("white").

1.11 Rows of squares or pins running lengthwise between the players are
called "files".

1.12 Horizontal rows of squares or pins at right angles to the files are
called "ranks".

1.13 The lines of like-colored squares at 45 degree angles to the files
are called "diagonals".

Section 2: Notation

Notation is used as an aid in explaining and interpreting these rules
as well as for recording games and playing games by correspondence.

2.1  The individual boards comprising the chessboard are identified as
follows:
WB - White's Board
NB - Neutral Board
BB - Black's Board
KL - White's attack board that, at the start of the game, is located
on the King's side of the Board (a.k.a. "King's Level").
kl - Black's attack board that, at the start of the game, is located
on the King's side of the Board.
QL - White's attack board that, at the start of the game, is located
on the Queen's side of the Board (a.k.a. "Queen's Level")
ql - Black's attack board that, at the start of the game, is located
on the Queen's side of the Board.

2.2  The squares are identified as follows:
The files are lettered from "a" to "f" from White's left to right, and
the ranks are numbered from "1" to "10" from White to Black. By
combining the file letter with the rank number, a square's two
dimensional location can be specified. See Figure 1. However, since
there are overlapping squares, it is usually necessary to include the
board notation (See Section 2.1) as a suffix to the square notation
(example: b4,WB). The recommended practice is to always include the
board notation. The notation for fixed-board squares is constant, but
the notation for attack board squares is dependent upon the attack
board's location. Example: When QL is positioned at QP1 (see Section
2.3), its square notations are a1,QL; b1,QL; a2,QL and b2,QL. But if
this board is moved to QP3, its square notations become a5,QL; b5,QL;
a6,QL and b6,QL.

2.3  The pins on the fixed boards are identified as follows:
KPn or QPn, where KP indicates a pin on the King's side of the board
and QP indicates a Queen-side pin; and where n indicates a specific
pin, the ranks of pins being numbered 1 through 12 from White to
Black with downward projecting pins always odd, and pins on any given
board numbered consecutively. See Figure 2.

2.4  Moves are described:
(a) in the case of a piece being transferred to a vacant square
without capturing another piece (see Section 6.6(c) for "en passant"
captures), by specifying the starting square's notation, followed by a
dash (-), followed by the ending square's notation;
(b) in the case of a piece making a capture, by specifying the
starting square's notation, followed by the letter x, followed by the
ending square's notation;
(c) in the case of an attack board being transferred to a vacant pin,
by specifying the starting pin's notation, followed by a dash (-),
followed by the ending square's notation;
(d) in the case of an attack board being rotated (see Section 7.2),
by specifying its pin notation, followed by the letter r.

Section 3: The Pieces

3.1 At the beginning of the game, one player has 16 light-colored
("white") pieces, the other has 16 dark-colored ("black") pieces. Each
player has the following types (and quantities) of pieces:
King   (1)
Queen  (1)
Rook   (2)
Knight (2)
Bishop (2)
Pawn   (8)

3.2  The initial arrangement of the pieces on the chessboard is shown
in Figure 3.

Section 4: The Right To Move

4.1  The player with the white pieces commences the game. The players
alternate in making one move at a time until the game is completed.

4.2  A player is said to "have the move" when his opponent's move
has been completed.

Section 5: The General Definition Of The Move

5.1  A move is:
(a) the transfer by a player of one of his pieces from its current
square to another square, which is either vacant or occupied by
an opponent's piece.
(b) the transfer by a player of one of his unoccupied attack boards
from its current pin to an adjacent vacant pin.
(c) the 180 degree rotation by a player of one of his attack boards
which is occupied by one or more pieces of either or both
players.

5.2  A piece played to a square occupied by an opponent's piece captures
it as part of the same move. The captured piece must be removed
immediately from the chessboard by the player making the capture
(see Section 6.6(c) for capturing "en passant").

5.3  No piece, except the Knight (Section 6.5), may cross a square
occupied by another piece. However, as part of any piece's move (as
defined in Section 6), it has complete freedom of movement between
boards as it progresses from square to square.

Section 6: The Moves Of The Pieces

For the moves described below, consecutive squares are defined as any
two squares whose notation (see Section 2.2) follows a logical
alphabetical progression (in the case of ranks), numerical progression
(in the case of files) or alphabetical and numerical progression
(in the case of diagonals), regardless of the board(s) on which the
squares are located. Example: b5,WB and b6,BB are consecutive squares;
but a2,QL and a9,ql are not; nor are b5,WB and b5,NB. See Figure 4.

6.1  The King.
The king moves to any consecutive square that is not attacked by an
opponent's piece.

6.2  The Queen.
The queen moves along a path of consecutive squares to any square
(except as limited by Section 5.3) on the file, rank, or diagonals
on which it stands.

6.3  The Rook.
The rook moves along a path of consecutive squares to any square
(except as limited by Section 5.3) on the file or rank on which it
stands.

6.4  The Bishop.
The bishop moves along a path of consecutive squares to any square
(except as limited by Section 5.3) on the diagonals on which it
stands.

6.5  The Knight.
The knight's move is composed of two different steps; first, it makes
one step of one single consecutive square along its rank or file, and
then, still moving away from the square of departure, one step of one
single consecutive square on a diagonal. It does not matter if the
square of the first step is occupied.

6.6  The Pawn.
(a) The pawn may move only forward (except as limited by Section
5.3).
(b) Except when making a capture, it advances from its original
square either one or two vacant consecutive squares along its
file, and on subsequent moves it advances one vacant consecutive
square along its file. When capturing, it advances one
consecutive square along either of the diagonals on which it
stands.
(c) A pawn attacking a square crossed by an opponent's pawn which has
just been advanced two ranks in one move from its original
square may capture this opponent's pawn as though the latter had
been advanced only one rank. This capture may only be made in
immediate reply to such an advance and is called an "en passant"
capture. The player making the capture may place his pawn on
either level within the limits specified in Section 5.1(a).
(d) On reaching his opponent's final fixed-board rank, a pawn must
immediately be exchanged, as part of the same move, for a queen,
a rook, a bishop, or a knight, of the same color as the pawn, at
the player's choice and without taking into account the other
pieces still remaining on the chessboard. This exchange of a pawn
for another piece is called "promotion", and the effect of the
promoted piece is immediate.

Section 7: The Moves Of The Attack Boards

7.1  An unoccupied attack board moves to any adjacent vacant pin, with
(a) two rank pins projecting from the same surface of the same board;
(b) two file pins projecting from the same surface of the same board;
(c) the two pins at the same corner of the same board;
(d) two facing pins at the same corner of two different adjacent
fixed boards;
(e) two facing pins at different corners but on the same (king or
queen) side of two different adjacent fixed boards.
Example: Pins adjacent to KP5 are QP5, KP7, KP6, KP2 and KP4. Pins
adjacent to KP1 are QP1, KP3 and KP2. See Figure 2.

7.2  An occupied attack board rotates 180 degrees.

Section 8: The Completion Of The Move

A move is completed:

8.1  in the case of the transfer of a piece to a vacant square, when the
player's hand has released the piece;

8.2  in the case of a capture, when the captured piece has been removed
from the chessboard and the player, having placed his own piece on
its new square, has released the capturing piece from his hand;

8.3  in the case of the promotion of a pawn, when the pawn has been
removed from the chessboard and the player's hand has released the
new piece after placing it on the promotion square. If the player
has released from his hand the pawn that has reached the promotion
square, the move is not yet completed, but the player no longer has
the right to play the pawn to another square;

8.4  in the case of the transfer of an attack board to another pin, when
the player's hand has released the attack board;

8.5  in the case of the 180 degree rotation of an attack board, when the
player's hand has released the attack board.

Section 9: Illegal Positions

9.1  If, during a game, it is found that an illegal move was made, the
position shall be reinstated to what it was before the illegal move
was made. The game shall then continue by applying the rules of
Section 8 to the move replacing the illegal move. If the position
cannot be reinstated, the game shall be annulled.

9.2  If, during a game, one or more pieces or attack boards have been
accidentally displaced and incorrectly replaced, the position before
the displacement occurred shall be reinstated, and the game shall
continue. If the position cannot be reinstated, the game shall be
annulled.

9.3  If a player moves and in the course of this inadvertently knocks
over a piece, or several pieces, or disorients an attack board, he
must re-establish their positions.

9.4  If, after an adjournment, the position is incorrectly set up, the
position as it was on adjournment must be set up again and the game
continued.

9.5  If, during a game, it is found that the initial position of the
pieces or attack boards was incorrect, the game shall be annulled.

Section 10: Check

10.1  The king is in "check" when the square it occupies is attacked by one
or more of the opponent's pieces; in this case, the latter is/are
said to be "checking" the king. A player may not make a move which
leaves his king on a square attacked by any of his opponent's
pieces.

10.2  Check must be parried by the move immediately following. If any check
cannot be parried, the king is said to be "checkmated" ("mated").

10.3  Declaring a check is not obligatory.

Section 11: The Completed Game

11.1  The game is won by the player who has checkmated his opponent's king.
This immediately ends the game.

11.2  The game is won by the player whose opponent declares he resigns.
This immediately ends the game.

11.3  The game is drawn when the king of the player who has the move is
not in check, and this player cannot make any legal move. The
player's king is then said to be "stalemated". This immediately ends
the game.

11.4  The game is drawn when one of the following endings arises:
(a)  king against king;
(b)  king against king with only bishop or knight;
(c)  king and bishop against king and bishop, with both bishops
on diagonals of the same color.
This immediately ends the game.

11.5  The game is drawn upon agreement between the two players. This
immediately ends the game.

11.6  The game is drawn when the same pattern of pieces appears for the
third time for a given player. The pattern is considered the same if
pieces of the same kind and color occupy the same squares, and if all
the possible moves of all the pieces are the same.

FIGURE 1
_ _ _ _ _ _             _ _ _ _ _ _
|     |     |           |     |     |
10 > |     |* * *|           |     |* * *|
|_ _ _|_ _ _|_ _ _ _ _ _|_ _ _|_ _ _|
|     |     |     |     |     |     |
9 > |* * *|  X  |* * *|     |* X *|     |
|_ _ _|_ _ _|_ _ _|_ _ _|_ _ _|_ _ _|
|     |     |     |     |
8 >       |* * *|     |* * *|     |
|_ _ _|_ _ _|_ _ _|_ _ _|
|     |     |     |     |
7 >       |  X  |* X *|  X  |* X *| <--
|_ _ _|_ _ _|_ _ _|_ _ _|    | Black's Board overlaps the
|     |     |     |     |    | Neutral Board on these ranks
6 >       |* X *|  X  |* X *|  X  | <--
|_ _ _|_ _ _|_ _ _|_ _ _|
|     |     |     |     |
5 >       |  X  |* X *|  X  |* X *| <--
|_ _ _|_ _ _|_ _ _|_ _ _|    | The Neutral Board overlaps
|     |     |     |     |    | White's Board on these ranks
4 >       |* X *|  X  |* X *|  X  | <--
|_ _ _|_ _ _|_ _ _|_ _ _|
|     |     |     |     |
3 >       |     |* * *|     |* * *|
_ _ _|_ _ _|_ _ _|_ _ _|_ _ _|_ _ _
|     |     |     |     |     |     |
2 > |     |* X *|     |* * *|  X  |* * *|
|_ _ _|_ _ _|_ _ _|_ _ _|_ _ _|_ _ _|
|     |     |           |     |     |
1 > |* * *|     |           |* * *|     |
|_ _ _|_ _ _|           |_ _ _|_ _ _|

^     ^     ^     ^     ^     ^
a     b     c     d     e     f

Asterisks (*) indicate dark squares.
X's indicate overlapping squares.
FIGURE 1

FIGURE 2
FRONT VIEW                                  SIDE VIEW

11          12
|___________|          black                      |___________|
|           |          board                      |           |
9           10

6           8
|___________|         neutral              |___________|
|           |          board               |           |
5           7

2           4
|___________|          white         |___________|
|           |          board         |           |
1           3
^           ^
QUEEN        KING
PINS         PINS

FIGURE 2

FIGURE 3
_ _ _ _ _ _             _ _ _ _ _ _
|     |     |           |     |     |
|  r  |* p *|           |  p  |* r *|
|_ _ _|_ _ _|_ _ _ _ _ _|_ _ _|_ _ _|
|     |     |     |     |     |     |
|* n *| p/b |* q *|  k  |*p/b*|  n  |
|_ _ _|_ _ _|_ _ _|_ _ _|_ _ _|_ _ _|
|     |     |     |     |
|* p *|  p  |* p *|  p  |
|_ _ _|_ _ _|_ _ _|_ _ _|
|     |     |     |     |
|     |* * *|     |* * *|
|_ _ _|_ _ _|_ _ _|_ _ _|
|     |     |     |     |
|* * *|     |* * *|     |
|_ _ _|_ _ _|_ _ _|_ _ _|
|     |     |     |     |
|     |* * *|     |* * *|
|_ _ _|_ _ _|_ _ _|_ _ _|
|     |     |     |     |
|* * *|     |* * *|     |
|_ _ _|_ _ _|_ _ _|_ _ _|
|     |     |     |     |
|  P  |* P *|  P  |* P *|
_ _ _|_ _ _|_ _ _|_ _ _|_ _ _|_ _ _
|     |     |     |     |     |     |
|  N  |*B/P*|  Q  |* K *| B/P |* N *|
|_ _ _|_ _ _|_ _ _|_ _ _|_ _ _|_ _ _|
|     |     |           |     |     |
|* R *|  P  |           |* P *|  R  |
|_ _ _|_ _ _|           |_ _ _|_ _ _|

LEGEND
Asterisks (*) indicate dark squares.
K - white king                       k - black king
Q - white queen                      q - black queen
R - white rook                       r - black rook
N - white knight                     n - black knight
B - white bishop                     b - black bishop
P - white pawn                       p - black pawn
B/P- white bishop over               p/b- black pawn over
white pawn                           black bishop

FIGURE 3

FIGURE 4
_ _ _ _ _ _             _ _ _ _ _ _
|     |     |           |     |     |
| a10 |*b10*|           | e10 |*f10*|
|_ _ _|_ _ _|_ _ _ _ _ _|_ _ _|_ _ _|
|     |  X  |     |     |  X  |     |
|* a9*|  b9 |* c9*|  d9 |* e9*|  f9 |
|_ _ _|_ _ _|_ _ _|_ _ _|_ _ _|_ _ _|
|     |     |     |     |
|* b8*|  c8 |* d8*|  e8 |
|_ _ _|_ _ _|_ _ _|_ _ _|
|  X  |  X  |  X  |  X  |
|  b7 |* c7*|  d7 |* e7*| <--
|_ _ _|_ _ _|_ _ _|_ _ _|    | Black's Board overlaps the
|  X  |  X  |  X  |  X  |    | Neutral Board on these ranks
|* b6*|  c6 |* d6*|  e6 | <--
|_ _ _|_ _ _|_ _ _|_ _ _|
|  X  |  X  |  X  |  X  |
|  b5 |* c5*|  d5 |* e5*| <--
|_ _ _|_ _ _|_ _ _|_ _ _|    | The Neutral Board overlaps
|  X  |  X  |  X  |  X  |    | White's Board on these ranks
|* b4*|  c4 |* d4*|  e4 | <--
|_ _ _|_ _ _|_ _ _|_ _ _|
|     |     |     |     |
|  b3 |* c3*|  d3 |* e3*|
_ _ _|_ _ _|_ _ _|_ _ _|_ _ _|_ _ _
|     |  X  |     |     |  X  |     |
|  a2 |* b2*|  c2 |* d2*|  e2 |* f2*|
|_ _ _|_ _ _|_ _ _|_ _ _|_ _ _|_ _ _|
|     |     |           |     |     |
|* a1*|  b1 |           |* e1*|  f1 |
|_ _ _|_ _ _|           |_ _ _|_ _ _|

Asterisks (*) indicate dark squares.
X's indicate overlapping squares.
FIGURE 4

The design of the chessboard pictured above is based on information given in the Starfleet
Technical Reference Manual, though it was modified slightly as indicated below:

A border was added around each of the three fixed boards. This allows the pins
for the attack boards to be positioned precisely on the corner of the outside
squares of each board instead of being offset as shown in the technical manual.
As a result of this change, the squares on the attack boards line up precisely
with the squares on the fixed boards, and allows attack boards to be mounted
tangentially. For example, it is possible to have two attack boards attached to
the King-side pins on the bottom of Black's Board and two attack boards attached
to the top pins on the King-side of the Neutral Board simultaneously, resulting
in a continuous 2 square by 8 square playing area.
The colors used for the squares on the playing board are clear (the "white"
squares) and frosted (the "black" squares) rather than clear and red as shown
in the Technical Manual.
The posts of Black's attack boards were frosted to eliminate confusion over
which boards belong to whom.
A cross symbol was added to the post of each King's attack board to eliminate
confusion over which board is which when playing by correspondence.

The chessboard is 26.625" high overall. The fixed boards are 9.625" square with an 8"
spacing between the top surfaces of adjacent fixed boards.
The bottom-most portion of the stand was made from the base of a microphone stand. The
remainder of the base is aluminum, and the circular frame is 0.5" steel bar stock. The
boards and corner pins are made of Acrylite, and the attack board posts are plexiglass
tubing.