Dual Chess

By Antoine Fourrière

Introduction

I am not a big fan of Grand Chess.

The Marshall is too strong.
The Marshall and the Cardinal are too similar. One is okay, but two feels somewhat redundant.
The Knight is much too weak on 10x10.
The Rooks are already connected.
Endgames without Queens, Marshalls or Cardinals are uncommon.

I find Capablanca Chess more appealing, but there are other issues, like having all the Pawns protected in the setup. And although the Knight is more valuable on 8x10 than on 10x10, the Rook becomes much stronger than the Bishop. True, Chess may lack a piece of intermediate value between the Queen and the Rook, such as the Cardinal. But the current variants whose purpose is simply to introduce a Cardinal and a Marshall are too different from Chess for my taste.

I also fail to understand why the Marshall and the Cardinal should be more legitimate alternatives to the Queen than the Berolina Pawn is to the Pawn.

There is another reason for my dislike of Grand Chess or Capablanca Chess. I wish to save a big chunk of Chess opening theory. Unfortunately, simply keeping the usual pieces on a 8x8 portion within a larger 8x10, 8x12 or 10x10 structure doesn't do the job, regardless of the new pieces. For instance, my own Chess on a Larger Board with not so few pieces dropped may start 1.e4 e5 2.Nf3 Nc6 3.Bb5... just to allow my brand of Murray Lion to jump on a6 and chase the Bishop away, so there is no Ruy Lopez. If I want to play the Pirc Defence at Jean-Louis Cazaux's Shako, it goes (let's assume that the Kings are on e1 and e8) 1.e4 d6 2.d4 Nf6, only to have White protect the Pawn on e4 with a Cannon instead of having to play Nc3 or f3. Such misfortune would happen also on David Paulowich's MRNBQKBNRM or George Duke's FRNBQKBNRF 10x8 Chancellor and Falcon arrays. The extra pieces shouldn't be able to reach the original setup in less than two or three moves.

Board and Setup

Dual Chess (not to be confused with Erez Schatz's Duel Chess, which happens to be also played on two boards) is played on a main 64-square board and a secondary 36-square board. The reunion of these two boards, though not the boards themselves, is cylindrical, that is, the main board and the secondary board are both to the left and to the right of each other, in the sense that a Knight may leap from the h file to the j file and vice versa, but also from the a file to the o file and vice versa.

setup

White: King (K): e1; Queen (Q): d1; Rooks (R): a1 h1; Knights (N): b1 g1; Bishops (B): c1 f1; Cardinal (C): l2; Marshall (M): m2; Guards (G): k2 n2; Pawns: a2 b2 c2 d2 e2 f2 g2 h2; Berolina Pawns: j3 k3 l3 m3 n3 o3

Black: King (K): e8; Queen (Q): d8; Rooks (R): a8 h8; Knights (N): b8 g8; Bishops (B): c8 f8; Cardinal (C): l7; Marshall (M): m7; Guards (G): k7 n7; Pawns: a7 b7 c7 d7 e7 f7 g7 h7; Berolina Pawns: j6 k6 l6 m6 n6 o6

The Pieces

The King, the Queen, the Rook, the Bishop, the Knight and the Pawn move as they do in International Chess, except that

A Knight is permitted to jump over a non-existent square.
A Bishop is permitted to commute neutrally between two corner squares, provided they are on the same side and of the same color (that is, between a1 and j2, between a8 and j7, between h1 and o2 and between h8 and o7).
A Pawn may only promote to a Rook, a Bishop, a Knight or a Pawn of Camel (somewhat reminiscent of Tamerlane Chess).

The Marshall and the Cardinal move as they do in Grand Chess, that is, as a Rook or a Knight and as a Bishop or a Knight.
(Like the Knight, they may jump over a non-existent square, but the Cardinal isn't permitted the above commuting Bishop move.)

The Berolina Pawn moves without capturing one square diagonally forward and captures one square orthogonally forward. Since it is restricted to (a part of) a 36-square zone, there is no double-step move. Like the Pawn, it may only promote to a Rook, a Bishop, a Knight or a Pawn of Camel. (Of course, a Rook won't be able to leave the secondary board.)

The Guard is a soon-to-be Wazir or Firz. (The Wazir and the Firz respectively move one square orthogonally and one square diagonally.) It moves (and captures) like a King. but becomes a Firz or a Wazir as soon as any Guard moves.
When a player moves a Guard orthogonally, both his Guards become Wazirs and both his opponent's Guards become Firzes (assuming no Guard has been captured, of course), but his opponent is allowed to turn immediately his Firzes into Wazirs. (This also counts as a move.). Conversely, when a player moves a Guard diagonally, both his Guards become Firzes and both his opponent's Guards become Wazirs, and the opponent is allowed to turn them immediately into Firzes.

The Camel is a colorbound leaper: it moves three squares in one direction and one square in another. Like the Knight and its compounds, it may jump between the main board and the secondary board.
The Pawn of Camel can't move, and is allowed only two actions:
It may promote to a Camel, and it may commit suicide while turning an enemy Marshall or Cardinal into a Camel.

Why these pieces?

There are roughly three kind of pieces: the usual array, the pieces of secondary interest (the Marshall, the Cardinal, the Berolina Pawn and perhaps the Camel) and the pieces which have been added as tuners.

The Marshall and the Cardinal are significantly weaker than the Queen, since they are several moves away from the King and run the risk of being turned into Camels. On the cramped secondary board, there is often a (not that) premature exchange of Cardinals and/or Marshalls.

The Guards are particularly useful.

They protect the Berolina Pawns, but are short-lived. (If I had given each player a pair of Princes -- non-royal Kings --, or a pair of Wazirs and a pair of Firzes, both players would simply rush their Marshalls and Cardinals to the main board, fully aware that the secondary board should remain closed.)
They usually, though not always, evolve into one pair of Wazirs and one pair of Firzes, which adds unbalance.
They prevent their own Marshalls from reaching the main board in two moves.
They protect their Marshalls, which in fact means just the contrary (that is, the -- diagonal -- move of both Marshall Berolina Pawns will result in a quick exchange.)

The Pawn of Camel is also a bit contrived. But if a Berolina Pawn could turn a Marshall or a Cardinal into a Camel regardless of being capturable on its promotion row, it would be too easy in my view. Conversely, if a Pawn reached its promotion row on a square where it couldn't be captured, the enemy Marshall or Cardinal would suicide itself at once on a Rook, Bishop or even Knight (maybe after moving at a Camel's leap of the Pawn owner's King or other piece), since a Camel is weaker than any of them, and the game would see no Camel at all.

Other rules

The game is conducted by the rules of International Chess, except where noted otherwise. Castling is unchanged. Stalemate or third repetition is a draw.

The play of the game

The opening should be quite akin to the opening theory of Chess, although the game is more dynamic. Debatable gambit openings should become sounder, either scoring a quick win or backfiring less definitively as usual.
(Of course, there still are differences. For instance, a Knight on the a or h file becomes more useful.)

There are two kinds of middle games. One features the same number of composed pieces (Queen, Marshall and Cardinal) for each player on both boards and is nearly as strategic as Chess (and certainly more strategic than Grand Chess or Capablanca Chess), the other is a race between mate on the main board and (immediately rewarding) demotions and (less immediately rewarding) promotions on the secondary board.

The endgame belongs to the Rooks, the Bishops and the Knights, since the Berolina Pawns are seldom promoted into Rooks.

Computer play

There is a zrf file.
Since Zillions doesn't take into consideration the position of a piece for its evaluation, I defined two kinds of Rooks, Bishops, Knights, Cardinals and Marshalls and added bogus points to give them different arbitrary values on the two boards. You can open the zrf and change the relative piece values with commands such as (1000-points) or (5000-points).

Written by Antoine Fourrière.

WWW page created: January 15th, 2006.