The Chess Variant Pages

Chess with Ultima, Rococo and Supremo Pieces


Three related Chess variants invented by George Deckle Sr. in 1986 are described in Pritchard's Encyclopedia of Chess Variants: Coordinator Chess, Immobilizer Chess and Withdrawer Chess. Each of these transplants the standard Orthochess array to a 10 x 10 board, and adds two pieces borrowed from Robert Abbott's game of Ultima between the Bishops and the Knights. These variants were perhaps inspired by a number of variants by the great V.R. Parton, such as Chimaera Chess, Gorgana Chess, Mimotaur Chess or Wyvern Chess, which also included an Orthochess array transplanted to a 10 x 10 board with exotic pieces added between the Bishops and the Knights. These games provides an interesting arena in which to test how these pieces interact with conventional Chess pieces.

In addition to these original three variants, I have added Long Leaper Chess, (and borrowing from Rococo), Advancer Chess and Swapper Chess, (and borrowing from Supremo) Pushme-Pullyu Chess.

I would have also added Chameleon Chess, using the Chameleon piece used in Ultima, Rococo and Supremo, but it has already been invented by V.R. Parton, and is called Mimotaur Chess (or Imitante Queen), and can be found below.

Board and Setup

All of these games have basically the same board and setup, as described above:

10 | r |:n:| ? |:b:| q |:k:| b |:?:| n |:r:|
 9 |:p:| p |:p:| p |:p:| p |:p:| p |:p:| p |
 8 |   |:::|   |:::|   |:::|   |:::|   |:::|
 7 |:::|   |:::|   |:::|   |:::|   |:::|   |
 6 |   |:::|   |:::|   |:::|   |:::|   |:::|
 5 |:::|   |:::|   |:::|   |:::|   |:::|   |
 4 |   |:::|   |:::|   |:::|   |:::|   |:::|
 3 |:::|   |:::|   |:::|   |:::|   |:::|   |
 2 | P |:P:| P |:P:| P |:P:| P |:P:| P |:P:|
 1 |:R:| N |:?:| B |:Q:| K |:B:| ? |:N:| R |
     a   b   c   d   e   f   g   h   i   j
White: Black:
If a1 is dark, then Queens are on opposite color rather than on color. These games can also be played quite nicely on a 10 x 8 board, with the same setup except with the two arrays closer together.

General Rules

The rules of all of these games are identical to those of Orthochess (AKA FIDE Chess AKA International Chess AKA Western Chess), except when noted otherwise.


The rules are incomplete in some areas. In particular, there is no mention of castling, Pawn initial move or Pawn promotion. The ECV says nothing about them, and most likely neither did the original sources.

It is probably simplest to assume that castling works as it does in most 10 x 8 or 10 x 10 variants, with the King moving three squares toward the Rook's square and the Rook leaping over to the King's far side.

The simplest assumption in the case of the Pawn's initial move is that it retains the normal Orthochess double-move. However, given the distance across the board, these games almost certainly play better if the Pawn's initial move is three squares -- with the corresponding possibilities for en passant capture -- as in Omega Chess. If played on a 10 x 8 board, the normal two-step Pawn initial move is sufficient.

Pawn promotion is more obscure. Almost all Chess variants on a 10 x 10 board have promotion occur the 10th row, and most Chess variants allow Pawns to promote to any type of non-Pawn, non-King piece that started on the board. Using these common rules for Pawn promotion should at least yield a reasonably playable game.

Coordinator Chess

In Coordinator Chess, the two added pieces are Coordinators, which move as Orthodox Queens but captures by 'coordinating' with the King. Upon completing a move, a Coordinator may remove an enemy piece with which (1) it shares a file, and (2) its King shares a rank (or vice versa). Thus, it is possible for a Coordinator to capture two pieces at once. (e.g.: King at a3, Coordinator moves to c7 and captures pieces at a7 and/or c3.) A Coordinator may never move to any occupied square. Animated Illustration. Coordinators come from Ultima.

Immoblizer Chess

In Immobilizer Chess, the two added pieces are Immbolizers, which moves as Orthodox Queens but do not capture. An enemy piece standing adjacent to an Immobilizer may not move while the Immobilizer is present. Black and white Immobilizers, occupying adjacent squares, are each frozen until the other is captured. An immobilized piece may 'commit suicide' by removing itself from the board, usually to open a line of attack. This counts as a move for the player removing the piece. An Immobilizer may never move to an occupied square. An Animated Illustration, and another Animated Illustration. Immobilizers come from Ultima.

Withdrawer Chess

In Withdrawer Chess, the two added pieces are Withdrawers, which move passively as Orthodox Queens. In order to capture, a Withdrawer must occupy a square adjacent to an enemy piece. To complete the capture, it must move one or more squares directly away from the enemy piece. For example, a Withdrawer moving from d2 to g2 captures only an enemy piece at c2 (not c3/d3/e3/c1/d1/e1). A Withdrawer may never move to an occupied square. An Animated Illustration and and another Animated Illustration. Withdrawers come from Ultima.

Advancer Chess

In Advancer Chess, the added pair of pieces are Advancers, which move passively as an Orthodox Queen. In order to capture, the Advancer must move to a square adjacent to an enemy piece. If the next square in the direction of movement from the square on which the Advancer stopped is occupied by an opposing piece, that opposing piece is captured; this is capture by approach. These captures are part of movement, and are not optional -- you can not move a Advancer next to an opposing piece in the line of movement and not capture it. An Advancer never moves to an occupied square. Animated Illustration. Advancers come from Rococo.

Long Leaper Chess

In Long Leaper Chess, the two added pieces are Long Leapers, which move as Orthodox Queens and capture by overtaking. They take possession of a single intervening piece by leaping to a vacant square somewhere beyond it. They may capture additional pieces, along the same line, if a vacant 'landing square' lies somewhere beyond each enemy piece. Long Leapers may never jump over a friendly piece, jump over two or more pieces with no empty spaced between, or move to an occupied square. An Animated Illustration and and another Animated Illustration. Long Leapers come from Ultima.

Pushme-Pullyu Chess

In Pushme-Pullyu Chess, the two added pieces are Pushme-Pullyus, which move like Queens, but never to an occupied square. If they move directly away from an adjacent opposing piece, they will capture it like a Withdrawer. If they move directly next to an opposing piece in their direction of movement, they will capture it like an Advancer. They may combine both types of capture in a single move. These captures are part of movement, and are not optional -- you can not move a Pushme-Pullyu directly away from an opposing piece and not capture it. Pushme-Pullyu's come from Supremo.

Swapper Chess

In Swapper Chess, the two added pieces are Swappers, which moves as an Orthodox Queen without capturing, or may swap position with any piece of either side an unobstructed Queen's move away. Additionally, a Swapper may capture an adjacent piece and itself at the same time by mutual destruction. Mutual destruction may not be used when immobilized. If a Swapper swaps with an opposing Swapper or Chameleon, on the following turn the two pieces may not swap back. They may swap again once any other move is made. Animated Illustration. The Swapper, without the capture by mutual destruction and without the ability to swap with friendly pieces in addition to enemy pieces, was called the Ximaera and the Chimaerine by V.R. Parton. If you remove capture by mutual destruction, and don't allow Swappers to swap with friendly pieces, then Swapper Chess becomes Chimaerine Chess; if you then make Swappers immune to capture as well, then the game becomes Chimaera Chess. Swappers come from Rococo.

There are some special rules for Pawns in Swapper Chess:

Mimotaur Chess

In Mimotaur Chess (also known as Imitante Queen Chess), the two added pieces are Mimotaurs, which move like Queens when not capturing, but capture other pieces as those pieces capture. So, it captures:
Pawns by a diagonal step forward (your forward, not the Pawn's);
Knights by a Knight's leap;
Bishops by a diagonal slide;
Rooks by an orthogonal slide;
Queens like either a Bishop or a Rook;
Kings by a move of a single square in any direction.
Mimotaurs can never capture other Mimotaurs. The Mimotaur and Mimotaur Chess were invented by V.R. Parton.

Notes and Comments

Peter Aronson's Comments

When I first looked at these variants, I was rather worried that they would match Ivan A. Derzhanski's "token comment" about Cuban Chaturang, that once the special pieces and maybe a Pawn or two had been exchanged, they would "degenerate into a conflict of two OrthoChess armies on a board that's too large for them." However, this does not seem to happen, and I think it is due to the fact that, with the exception of the Mimotaur, none of the exotic pieces capture by replacement: this seems to reduce the chances of the pieces being exchanged.

This page, and the Zillions Rules File below is a result in part of Ben Good's work on the Piececlopedia, as he requested a ZRF with the first three games as part of his work in revising and updating the Ultima and Rococo entries, and then I threw the others in on general principles.

Ben Good's Comments

My original concern was that the Withdrawer, Advancer, Pushme-Pullyu, Long-Leaper, and possibly even the Coordinator and Immobilizer would all be too powerful in this context. Pawns seemed especially helpless - since they are not mobile like Ultima and Rococo Pawns, they can not escape threats easily, nor can they capture an Immobilizer, and since the added pieces don't capture by displacement, the Pawn can't be protected by direct defense.

Zillions does consider the W, A, PP, and L to be all worth about a Pawn less than a Queen, although I can't understand why the W, A, and PP all have almost exactly the same value, another quirk of the Zillions thinking process. Even more mysterious is that the Chimaerine and Swapper are both valued at more than a Q, even though for the most part they don't capture. Zillions will trade any piece for Swappers, but it can't win with them, and it doesn't use them effectively for moving pawns into position to promote. Swapper and Chimaerine Chess are the only variants at which I can easily beat Zillions at the highest setting. Zillions considers the Immobilizer almost equal to a Rook, but gives the Coordinator as barely more than a Knight. It also values the Mimotaur as a Pawn less than a Queen.

A good explanation for why the additional pieces aren't traded off early is because they are generally high in value - the basic chess concept of developing weaker pieces first applies to these games as well. But also important is the fact that in general, all these pieces, except possibly the Mimotaur, are much more effective towards the end of the game than the beginning. The strength of the W, A, L, Co, and PP is that they usually have multiple squares to which they can move to capture a given piece. The more open the board is, the less likely it is that these squares are guarded or blocked. Although the Immobilizer is more likely to be able to paralyze several pieces at once on a more crowded board, it also is less likely to be driven away once it's in place, and it's more likely to have a clear path to the opponent's King. The Swapper is more useful in the end because the can swap pawns to the 7th rank, where they are just one move away from promotion.

But I also found that there are ways to defend against all these pieces. None of them completely dominate the game or are totally unstoppable like I feared they might be. Although my initial interest was a somewhat academic 'testing' of these pieces in the context of standard chess pieces, I've found all these games to be enjoyable to play. I hope to provide some more detailed analysis in the future.

Computer Play

I have written a Zillions of Games Rules File with all of the above games. You can download it here:

The implementation uses the recommended castling and Pawn rules above, and all variants can be played on 10 x 10 boards or 10 x 8 boards.

Written by Peter Aronson, with some material and editing by Ben Good.
WWW page created: September 2nd, 2002.