The Chess Variant Pages

Check out Expanded Chess, our

featured variant for September, 2023.

This page is written by the game's inventor, Antoine Fourrière.

Chessma 84

By Antoine Fourrière


Chessma 84 is a Siamese-twin mixture of Orthochess and Ultima, and an entry for the 84-square contest.

The 84-square board is represented by two 68-square chessboards. Those chessboards have been added the same four corner squares, like in Omega Chess. They also share their second to seventh lines. Only their first and eighth lines differ.

On those lines, one board carries Orthochess pieces, which capture by replacement, exactly as they walk. The other board carries Ultima-style pieces, which usually don't capture by replacement.

The Pawns, which capture by replacement, though with a different move, start on the common part of the Chess board and the Ultima board. (Anyway, those boards are the Chess board and the Ultima board only in the opening. All pieces are allowed to walk everywhere, provided their moves take place entirely on at least one of the boards and don't put the King in check on the other.)

Board and Setup

The files are labeled 0, 1 and 1', 2, 3, 4, 5, 6, 7, 8 and 8', 9.
The corner squares are z0, z9, i0 and i9.



King (K): e1
Queen (Q): d1
Rooks (R): a1 h1
Bishops (B): c1 f1
Knights (N): b1 g1
Immobilizer (I): a1'
Pusher (P): b1'
Long Leaper (L): c1'
Withdrawer (W): d1'
Coordinator (C): e1'
Encloser (E): f1'
Swapper (S): g1'
Chameleon (X): h1'
Pawns: a2 b2 c2 d2 e2 f2 g2 h2
King (K): e8
Queen (Q): d8
Rooks (R): a8 h8
Bishops (B): c8 f8
Knights (N): b8 g8
Immobilizer (I): a8'
Pusher (P): b8'
Long Leaper (L): c8'
Withdrawer (W): d8'
Coordinator (C): e8'
Encloser (E): f8'
Swapper (S): g8'
Chameleon (X): h8'
Pawns: a7 b7 c7 d7 e7 f7 g7 h7

The Pieces

The King, Queen, Rooks, Bishops, Knights and Pawns move as they do in International Chess. A Knight may jump to a corner square.

The other pieces come from Ultima and its variants, with some minor changes.

They all move neutrally like the Queen.


The game is conducted by the rules of International Chess, except where noted otherwise.

A move must be complete on at least one of the checkboards. To put it another way, a Rook in d1 may go to h1 or d8, but not to c1', d1' or d8'. Of course, a Rook in d2 could, because d2 and d2' are just the same square. If, say, a white Bishop in d4 and a black Long Leaper in i9 face each other on a long diagonal of only one of the boards, because there's a black Coordinator in h8', but nothing in c3, e5, f6, g7 or h8, both pieces may capture each other.

A piece may never capture or immobilize a friendly piece. Only the Swapper and, as a collateral result, the Pusher may affect the status of a friendly piece. (If an Immobilizer and another piece change relative positions, the other piece is paralysed or freed. If a friendly or enemy Coordinator - or Withdrawer or Encloser - is moved, nothing happens.)

Ultima captures are not optional. A Withdrawer may not withdraw from a piece without taking that piece. A Coordinator has to take whatever it coordinates. An Immobilizer immobilizes adjacent pieces, even if this results in a stalemate.

A stalemate on a corner square is a win for the stalemating player. A stalemate elsewhere is a draw.

A Pawn may promote on either eighth file into any piece. If a Swapper swaps a Pawn to promotion, the owner of the Swapper chooses how to promote it, as opposed to standard Rococo. Pawn swap promotion also occurs on the corner squares (not the Pawn's corner squares). If a Pawn is swapped to its side's first or second line, it may run up to the fourth file in one move (and extended en passant applies).

Castling is unaffected.

The Play of the Game

Many pieces are stronger on defense than offense. The somewhat twisted nature of the board also plays a role. This is why some of the more defense-oriented Ultima pieces have been weakened.

The Pawns become overprotected. For instance, in the opening setup, the Chameleons and the Swappers may prevent the Knights from taking the f-pawns. Still, the Queens and the Bishops would take the Swappers back.

The Rooks run into many difficulties, even though King and Rook mates. They can't reach voluntarily the corner squares. When on the seventh line, they are vulnerable to a sneak attack from the two eighth lines. They are the choice victims of the Enclosers, which capture mostly by moving next to a1, a1', h1, h1', a8, a8', h8, h8', which have only two side neighbors. (Likewise, moving a Knight to h7 may check a King on h8', provided g8' is free and the Encloser hasn't captured or been captured.)

The Bishops are nearly as strong as the Rooks. A Bishop on its second or third line has more room, even outside the main diagonals. A Bishop on a central square controls more squares than a Rook, even outside the first and eighth lines (18 to 16, where it was 13 to 14).


Cxz9 means that the Coordinator has taken one piece in coordination with the King by moving to z9. (That King is lurking in i0.)
Sxg3 means that the Swapper has swapped with a piece and is now in g3.
Ixxh5 (2) (or I*h5 (2)) means that the Immobilizer has immobilized two pieces by its move to h5.
Lxxi9 (6) means that the Long Leaper has reaped six pieces, four of which were necessarily on a1, a1', h8 and h8'.
Wxxg5 means that the Withdrawer has withdrawn (only two) pieces by going to g5. (c1 and c1' from d2, for instance).
Xxxd5 (2) means that the Chameleon has captured two pieces, one of which may have been there, or captured one piece (or pushed a Pusher or swapped a Swapper) and immobilized an adjacent Immobilizer by its move. (Yes, it may mimic an Ultima take or immobilization, even the Enclosure of an Encloser, and still land on an occupied square, although that's debatable.)
Exxd4 (3) means that the Encloser has enclosed three pieces which are now "pocket pieces" for its owner, and =Ra7 means that the Pocket Rook has gone back to business.

Written by Antoine Fourrière.
WWW page created: October 4th, 2002.

Last modified: Monday, September 23, 2002