Obento Chess

This large chess variant is the fruit of a collaboration between Eric Silverman and Jean-Louis Cazaux. Silverman had the initial idea of blending elements of large shogis into a giant Western styled chess variant, with the incorporation of bent-riders such as the Osprey and the Ostrich. Both inventors selected the pieces together, and defined their promotions after some very animated discussions. They elaborated the name of the game as a pun, recalling the presence of bent-riders in a Japanese manner.

The setup and promotion rules have been fixed after numerous tests with the help of the AI AI tool (Silverman has coded dozens of chess variants in AI AI).

Setup

The dozenal board of 12x12 squares is used for Obento Chess. Each side has 36 pieces positioned on the first three rows of each player.

• The 3rd row is occupied by 12 Pawns.
• The 2nd row has the King (g2), Queen (f2), Bishops (e2, h2), Marquis (d2, i2), Gold Pashtuns (c2, j2), Silver Pashtuns (b2, k2) and Rooks (a2, l2).
• On the 1st row there are Ostriches (a1, l1), Snakes (b1, k1), Wizards (c1, j1), Ships (d1, i1), Ospreys (e1, h1) and Wildebeests (f1, g1).

Black mirrors White's pieces.

Initial Setup:

Pieces

King: moves 1 step in every (8) directions on a not attacked square. The King is in check if it is attacked by one or several enemy pieces. It is forbidden to play a move letting his King in check. Apart from castling (see below), it is identical to standard chess.

Queen: slides to any square along the file, the rank, or a diagonal on which it stands. Identical to standard chess.

Rook: moves to any square along the file or the rank on which it stands. Identical to standard chess (except there is no castling). May promote to Dragon King.

Bishop: slides to any square along a diagonal on which it stands. Identical to standard chess. May promote to Dragon Horse.

Marquis: it replaces the Knight, as in Opulent Chess. It moves and captures as the Knight or as a Wazir, i.e. one step orthogonally. May promote to Squirel.

Gold Pashtun: moves one or two squares orthogonally or forward diagonally, leaping over the intervening square if it is occupied. May promote to Gold Rider.

Silver Pashtun: moves one or two squares in five directions, diagonally or straight forward, leaping over the intervening square if it is occupied. May promote to Silver Rider.

Wildebeest: combines the moves of the chess Knight and Camel as in Wildebeest Chess. May promote to Wildeguard.

Osprey: leaps to the second square orthogonally (the Dabbaba's leap), then slides outward diagonally like the Bishop. This piece is also found in Expanded Chess.

Ship: a piece also used in Tamerlane II. It moves one square diagonally and then, goes away of an indefinite number of cases vertically, never horizontally. It can move one square diagonally only. It can not jump and must begin its move with the diagonal step. May promote to Ostrich.

Wizard: leaps like the Camel or moves one square diagonally like a Ferz. It is a color-bound piece used in Omega Chess and several subsequent variants. May promote to Caliph.

Snaketongue: it moves one square vertically and then, slides away of an indefinite number of squares diagonally. It can not jump and the unobstructed path must start with the vertical movement. The Snake is the counterpart of the Ship. Both pieces are constrained bent-riders because the vertical direction is favored compare to the horizontal one in the definition of their moves. The name of this piece comes obviously from its move in shape of snake's tongue, an idea inspired from Ralph Betza. This piece is simply called Snake in Fantastic XIII. May promote to Osprey.

Ostrich: another bent-leaper-rider, which first leaps to the second square diagonally (the Alfil's leap), then slides outward orthogonally like the Rook.

Pawn: it may step one, two or three squares forward on its first move; after that, only one square at a time. The Pawn may not move one square initially and then two on a later move (as it does in some variants). It captures one square diagonally forward identically to standard chess. May promote to Flying Ox and nothing else.

In addition to these pieces present in the starting line-up, there are eight others that appear by promotion. They are the Caliph, Dragon Horse, Dragon King, Flying Ox, Gold Rider, Silver Rider, Squirrel and Wildeguard.

Dragon King: it is another compound piece that moves as a Rook or a non-royal King. That means that it is a Rook that can also step one space diagonally. It is found in Shogi.

Dragon Horse: it is another compound piece that moves as a Bishop or a non-royal King. That means that it is a Bishop that can also step one space orthogonally. It is found in Shogi.

Squirrel: also a compound piece that jumps as a Knight or jumps at 2 squares, diagonally (like an Alfil) or orthogonally (like a Dabbaba).

Gold Rider: slides in the same six directions as the Gold Pashtun.

Silver Rider: slides in the same five directions as the Silver Pashtun.

Wildeguard: leaps like the Wildebeest or steps like the King.

Caliph: compound that leaps like the Camel or slides like the Bishop.

Flying Ox: slides diagonally or vertically, never horizontally. This piece is found in Chu Shogi.

Rules

En passant capture is possible whenever a Pawn, by either by a double or triple step, passes through a square controlled by an opposing Pawn. Apart from this, the Pawn’s rules remain standard.

Castling: the King may castle with either Rook by stepping three squares towards it while the Rook leaps to one square past the King, so that the King and Rook end up adjacent to each other. Restrictions are the same as in chess.

Promotions: not only the Pawns, but several other pieces may be promoted, on entering the last three rows of the board. The Pawn promotes to the Flying Ox, and this promotion is compulsory. The other promotions are optional as in traditional shogi. A piece may be promoted upon completion of a move partially or completely done in the promotion zone. There are Marquis to Squirrel, Ship to Ostrich, Snake to Osprey, Wizard to Caliph, Wildebeest to Wildeguard, Bishop to Dragon Horse, Rook to Dragon King, Silver Pashtun to Silver Rider and Gold Pashtun to Gold Rider. This is illustrated in the table below:

Notes

Obento Chess is influenced by Japanese shogi and its large variants. This starts with the promotion zone, which covers all the starting rows of the opponent. The idea of extending the promotion to many non-Pawn pieces is also borrowed from large shogi games. Some pieces come directly from shogi (the Rook and the Bishop promoting to Dragon King and Dragon Horse) or from Chu Shogi (the Flying Ox).

The Gold and Silver Riders are found in Maka Dai Dai Shogi, a very large shogi variant on a 19x19 board under the respective names of Free Gold and Free Silver.

The Gold and Silver Pashtuns are not found in historical large shogi variants but evidently inspired by the Gold and Silver Generals found in the Japanese games. They were defined by Charles Gilman in Generalised Generals / Long‐Nosed Generals and used in Pashtun Shogi. The Silver Pashtun was earlier known as the Great Elephant in White Elephant Chess.

Obento Chess also owes a debt to other chess variants. The Pawn's move is from Omega Chess, and so is the Wizard. The Wildebeest is from the variant of the same name. The Marquis is found in Scirocco. The Caliph is also a fairy piece found in many variants.

But the emblematic pieces of Obento Chess are the different bent-riders. The Ship and the Snake are also found in Fantastic XIII. The Osprey is from Expanded Chess but its counterpart, the Ostrich, is more original.

More chess variants

Extending this idea, Eric Silverman has designed a full family of giant variants of different size. Given that Obento Chess is named from bento, a meal that the Japanese might take to work or school, he has proposed:

• Hyaben Chess (10x10): from a quick, small bento meal for the busy employee.
• Teishoku Chess (14x14): from a traditional sit-down meal of multiple dishes, eaten at a restaurant.
• Chanko Chess (16x16): from a very hefty meal traditionally eaten by sumo wrestlers. The last game above involves 45 different pieces!

Eric Silverman has coded most of the chess variants that are available to play online on the AI AI platform. That includes all his own games, which may be tested there.

Last revised by Jean-Louis Cazaux.