The Chess Variant Pages




Ben39

Copyright 1998 Ben Good

Ben39 is a chess variant played on a 39 square chess board.

The game is played on a checkered board is shown in ASCII below. ::: represents dark squares, ### represents some other color that is distinguishable from the light and dark squares.

       +---+---+---+---+
       |###|:::|   |:::|     
       +---+---+---+---+---+ 
       |:::|   |:::|   |:::|   
   +---+---+---+---+---+---+---+
   |:::|   |:::|   |:::|   |:::| 
   +---+---+---+---+---+---+---+
   |   |:::|   |:::|   |:::|   |
   +---+---+---+---+---+---+---+
   |:::|   |:::|   |:::|   |:::| 
   +---+---+---+---+---+---+---+
       |:::|   |:::|   |:::|  
       +---+---+---+---+---+
           |:::|   |:::|###|   
           +---+---+---+---+

Play is on both the squares, like in chess, and on the intersections of the lines that make the squares, like in xiangqi. Thus, the notation system must accommodate this as shown below:

15      +---+---+---+---+
14      |###|:::|   |:::|     
13      +---+---+---+---+---+ 
12      |:::|   |:::|   |:::|   
11  +---+---+---+---+---+---+---+
10  |:::|   |:::|   |:::|   |:::| 
9   +---+---+---+---+---+---+---+
8   |   |:::|   |:::|   |:::|   |
7   +---+---+---+---+---+---+---+
6   |:::|   |:::|   |:::|   |:::| 
5   +---+---+---+---+---+---+---+
4       |:::|   |:::|   |:::|  
3       +---+---+---+---+---+
2           |:::|   |:::|###|   
1           +---+---+---+---+
   a b c d e f g h i j k l m n o

Each player begins with the following army:

5 Chad Rooks (X)
3 Pawns (P)
2 Spiders (Z)
2 Wizards (W)
2 Castles (C)
1 Immobilizer (I)
1 King (K)
1 Rook (R)
1 Bishop (B)
1 Knightrider (N)
1 Gold General (G)
1 Silver General (S)

The K, R, B, N, G, S, and P's play on the squares. They can never move off the squares onto the lines. The R moves like its counterpart in chess (there is no castling). The B does also, but it additionally it can move a single orthogonal square, provided it is a non-capturing move. The P's move like chess pawns except w/o the initial double-step (thereby eliminating en passant as well). Pawns moved to the last rank promote to Queen, which moves like a chess Queen. The knightrider moves like the well-known fairy-chess piece. The G and S move like their counterparts in shogi. The K moves like a chess king, but will have additional restrictions on it described below.

Ben39 is played with drops like shogi. If any of the pieces on the squares (other than the K) is captured, it becomes a piece-in-hand for the capturing player. Dropping a piece counts as a turn. Captured Q's are dropped on the board as P's. A piece can not be dropped on a square where it can not move. Dropping a P on a file where there is already an unpromoted P is legal, as is giving checkmate with a dropped P and dropping a P on the first rank.

The starting setup is shown below. The remaining pieces are held in reserve, and will be entered during the course of the game.

15      +---+---+---+---+
14      |###|*S*|*K*|*G*|     
13      +---+---+---+---+---+ 
12      |:::|*R*|*N*|*B*|:::|   
11  +---+---+---+---+---+---+---+
10  |:::|   |*P*|*P*|*P*|   |:::| 
9   +---+---+---+---+---+---+---+
8   |   |:::|   |:::|   |:::|   |
7   +---+---+---+---+---+---+---+
6   |:::|   |:P:| P |:P:|   |:::| 
5   +---+---+---+---+---+---+---+
4       |:::| B |:N:| R |:::|  
3       +---+---+---+---+---+
2           |:G:| K |:S:|###|   
1           +---+---+---+---+
    a b c d e f g h i j k l m n o

The remaining pieces are played on the intersections of the lines forming the squares. The can never move onto the squares, they can never capture other pieces, and they can never be captured.

Each player gets 5 Chad Rooks. The X's move along the lines like xiangqi rooks, but like the rooks in Chad, can not capture or be captured - they simply block each other and other pieces.

Each player gets 1 Immobilizer. The I moves like a Q, orthogonally or diagonally across the intersections of the lines. The I can not capture or move to occupied squares. Instead, the I immobilizes enemy pieces on the squares that form the intersection that the I is on.

5   +---+---+---+---+---+---+
4       |:::|*N*|*K*| N |:::|  
3       +---+---+---+---+--*I
2           |:G:| B |:::|  
1           +---+---+---+
    a b c d e f g h i j k l m n 

In the diagram above, black is in check from the G on f2. Black can remove check by moving his I from m3 to either g3 or e3, immobilizing the G.

Like all line pieces, the I starts off the board and reserve and is entered by drop. It is illegal for a player to drop his I such that it immobilizes an enemy piece immediately upon being placed.

Each player gets 2 Wizards. The W moves like a chess K, to any adjacent intersection. Like all line pieces, the W can not capture or move to occupied squares.

The W can be used to teleport pieces on the squares. Specifically, a W on an intersection can teleport any friendly piece on one of the squares that form the intersection that the W is located on. The piece is then teleported to the corresponding square relative to the player's other W. If a piece is teleported to a square occupied by a friendly piece, then that piece moves to the square just vacated by the teleporting piece. If the destination square is occupied by an enemy piece, then that piece is captured. If teleportation would result in the piece being teleported being off the board, the then that piece becomes a piece-in-hand for the teleporting player. A King in check may be teleported, but a K can never be teleported off the board. Enemy pieces can not be teleported. Players with only one W on the board can not use it to teleport.

7   +---+---+---+---+---+---+---+
6   |:::| P |:B:|   |:::|   |:N:| 
5   +---+---W---+---+---+---W---+
4       |:R:| S |:::|   |*G*|
3       +---+---+---+---+---+
2           |:::|   |:::|   
1           +---+---+---+
    a b c d e f g h i j k l m n o

In the diagram above, the W on e5 can teleport the P on d6 to l6. It can NOT teleport the P to l4 or n6, because it must teleport to the same relative position to the other W. The on f6 can be teleported to the n6, which would put the N on f6. The R on d4 could be teleported to l4, capturing the black G. The S on f4 could teleported off the board, and would become a piece-in-hand for white.

Each player gets 2 Spiders. The Z moves like a xiangqi knight, except that it is not blocked by intervening pieces. Like all line pieces, the Z can not capture or move to occupied squares.

The Z can be used to move the pieces on the squares. Specifically, a Z on an intersection picks up all friendly pieces on the squares that form the intersection that the Z is located on. It then rotates them all exactly one square in either the clockwise or counterclockwise direction. Enemy pieces are not moved. If a friendly piece lands on a square occupied by an enemy piece, then that piece is captured. Thus it is possible to capture two pieces in one turn using the Z. If a friendly piece is moved off the board, it becomes a piece-in-hand for that player. A player is not allowed to 'selectively rotate' - that is, the Z must pick up all friendly pieces, it can not move some and not move others that are within its zone of influence. A King in check can be rotated out of check.

5   +---+---+---+---+---+---+---+
4       |:::| B |:::| R |*G*|  
3       +---+---Z---+---Z---+
2           |:::| K |:S:|    
1           +---+---+---+
    a b c d e f g h i j k l m n o

In the diagram above, the Z on g3 can rotate the B and K. If it rotates CW, then the B if moved to h4 and the K to f2. If it rotates CCW, then the B is moved to f2 and the K to h4. Note that the Z only rotates 90 degrees, not 180, so that it is illegal for the B and K to be moved from their current positions to h2 and f4 respectively, in one turn. Also, it is illegal to rotate the K to h4 or f2 without also rotating the B to the corresponding square.

The Z on k3 can rotate CW, moving the R to l4, capturing the G. The Z on k3 can also rotate CCW, moving the S off the board, so that it becomes a piece-in-hand for that player.

Each player gets 2 castles. A castle moves either a single intersection orthogonally or a single intersection diagonally, depending on what it did its previous move. If it moved orthogonally on its last move, then it must move diagonally on its next, and vice-versa. I recommend using some kind of marker that can be flipped over to indicate which kind of move the castle will make next. When the castle is first placed on the board, the player placing it must decide which way it will move first.

The castle does not capture or move pieces. It is important because of the King rule: The King can only move or be moved to or from a square that has a friendly castle on one of its corners.

5   +---+---+---+---+---C---W---+
4       |:::|   |:::|   |:::|  
3       +---+---C---W---+---+
2           |:::| K |:::|    
1           +---+---+---+
    a b c d e f g h i j k l m n o

In the diagram above, the K move to f2, f4, g4, or j4. It can not move to j2, because there is no castle on any of that squares corners. The King can also be teleported to l4.

5   +---+---+---C---+---+---+---+
4       |:::|   |:::|   |:::|  
3       +---+---+---Z---C---+
2           |:::| K |:::|    
1           +---+---+---+
    a b c d e f g h i j k l m n o

In the diagram above, the K is immobilized. Since there are no C's on any of the corners of the square on which the K is currently located, the K can not move, even tho direct movement or Z-rotation could otherwise take it to squares with C's on their corners.

Note that altho the K can not move away from the C's, the C's can move away from the K (altho this is not recommended).

Besides the 37 checkered squares, there are two special squares which are movable. In the diagram at the beginning of the instructions, they are marked ### and start in the position shown in the opening setup diagram. So on a player's turn, he can do any of the following:

  • move a piece
  • drop a piece
  • move a movable square

There only 8 possible locations for the movable squares, as shown in the diagram below:

15      +---+---+---+---+---+
14      |###|*S*|*K*|*G*|###| 
13  +---+---+---+---+---+---+---+ 
12  |###|:::|*R*|*N*|*B*|:::|###|
11  +---+---+---+---+---+---+---+
10  |:::|   |*P*|*P*|*P*|   |:::| 
9   +---+---+---+---+---+---+---+
8   |   |:::|   |:::|   |:::|   |
7   +---+---+---+---+---+---+---+
6   |:::|   |:P:| P |:P:|   |:::| 
5   +---+---+---+---+---+---+---+
4   |###|:::| B |:N:| R |:::|###|  
3   +---+---+---+---+---+---+---+
2       |###|:G:| K |:S:|###|   
1       +---+---+---+---+---+
    a b c d e f g h i j k l m n o

When moving a square, the following rules apply:

  • The square moved can only be moved to one of the two nearest locations. For example, the square on l2 can only be moved to n4 or d2.
    The only exception to this rule is if one of the two locations is occupied by the other movable square, in which case the square moved can 'skip over' the other to the next nearest location. For example, if the two movable squares were at l2 and n4, the one on l4 could be moved directly to n12, and the one at n4 could be moved to d2.
  • The two squares can never be moved to the same location.
  • A movable square can only be moved if he controls that square. That means that the total number of pieces that that player has on the square and on the four corners of that square is greater than the total number of pieces of his opponent. Thus a totally unoccupied movable square can not be moved. An immobilized piece on the square does not count towards the player's total, nor does a K with no castle.
  • The piece on the square automatically travels with the square, as does the piece on the 'outside' corner of the square. Enemy pieces on the other 3 corners do not move. Friendly pieces move at the discretion of the player moving the square, provided their destination locations are empty - moving a square can not be used to capture.

5   X---*I--+---+---+---+---+---+
4   |#G#|:::|   |:::|   |:::|  
3   X---*Z--+---+---+---C---X
2           |:::|   |:::|#K#|   
1           +---+---+---*X--*C
    a b c d e f g h i j k l m n o

In the diagram above, the square on b4 can not be moved because neither player controls it. White's piece total is only two, since the G is immobilized by the I on c5.

White controls the square on l2, by a count of two to three. White can move the square to n4, the next location. In doing so, Black's C on m1 will automatically travel with the square, ending on o3, but the X on k1 will stay put. The White X can either stay on me or travel to o5, depending on White's preference. The C on k3 must travel to m5, because otherwise White will be moving his K to a square w/o a C. Likewise, White can not move the square to d2, because c3 is occupied by Black's Z, which block's White's C from travelling along.

Object of the game is to capture the opponent's K.

This game has not yet been playtested and may contain flaws.


Written by Ben Good, (c) 1998. Converted to HTML by Hans Bodlaender.
This is a submission to the contest to design a chess variant on a board with 39 squares.
WWW page created: December 7, 1998.