Hook Shogi

Hook Shogi (鉤行将棋 kōgyō shōgi, "hook mover shogi") is a 16x16 variant inspired by the hook movers from the largest Shogi variants (Dai Dai Shogi and up). It includes all four hook-moving pieces (the Hook Mover, Tengu, Capricorn, and Peacock), as well as an expanded version of the anti-trading rules for the Tengu from Tengu Dai Shogi to ensure at least one survives until the very end. Another powerful pair of pieces present in this game are Maka Dai Dai Shogi's Deva and Dark Spirit, which have contagious promotions, to Teaching King and Divine Spirit (same as Buddhist Spirit, just named differently), respectively. Also present are the Lion Dog, which promotes to a Great Elephant (which moves as a Lion or a Lion Dog), and the Roaring Dog (which promotes to a Lion Dog) from Taikyoku Shogi, which has a jump and step move akin to that of the Heavenly Tetrarch from Tenjiku Shogi.

Setup

An interactive diagram has been provided (The Javascript source code was written by H. G. Muller) to make it easier to understand how each piece moves. The Mnemonic piece directory uses H. G. Muller's Mnemonic pieces. The white Shogi pieces used in the diagram and the Pieces section are my own pieces, made using a free online pixel art drawing tool called Pixilart.

Only the location of the pieces of one side are mentioned below. The setup for the other side can be obtained by rotating the board 180 degrees. The promotion and XBetza notation of each piece has been included in brackets for easier reference ([R] indicates that the piece has restrictions on its movement or abilities, and [C] indicates a piece that has a contagious promotion).

Lines below can be clicked to see how the pieces move:

Pieces

The move of pieces from the initial setup is already given in Betza notation above, and should also be clear from the mnemonic piece glyphs in the diagram. Some pieces that move in special ways are discussed below.

Hook Mover

The Hook Mover is a Rook that can (but does not have to) make one 90-degree turn in its path. Like any slider, it has to stop at the point where it captures, and the (bent) path it moves along must be empty up to that point.

It cannot capture a Hook Mover, Tengu, Capricorn, or Peacock.

Capricorn and Tengu

The Capricorn and Tengu are Bishops that can (but do not have to) make one 90-degree turn in their paths. Like any slider, they have to stop at the point where they capture, and the (bent) paths they move along must be empty up to that point.

The Tengu can in addition move one square orthogonally.

They cannot capture a Hook Mover, Tengu, Capricorn, or Peacock.

Peacock

The Peacock moves one or two squares diagonally backward, and slides diagonally forward, in addition, when sliding along one of the forward diagonals, it can (but does not have to) make one 90-degree turn in its path. Like any slider, it has to stop at the point where it captures, and the (bent) path it moves along must be empty up to that point.

It cannot capture a Hook Mover, Tengu, Capricorn, or Peacock.

Lion, Lion Hawk, and Divine Spirit

The Lion, Lion Hawk, and Divine Spirit are double movers: they can make up to 2 King steps per turn, changing direction between them, even when this returns them to their starting square. They can make the first step as a jump, when they choose to do so. So each of them can:

• Jump directly to any square in the 5x5 area surrounding it,
• Annihilate any opponent standing next to it, without moving (formally one step, and then a step back),
• Annihilate any opponent standing next to it, moving on to an empty square next to that ('hit and run'),
• Annihilate any opponent standing next to it, and normally capture an opponent standing next to that ('double capture'),
• Stay in place without capturing anything if one of the neighboring squares is empty (effectively passing a turn)

The Lion Hawk and Divine Spirit can in addition move as a normal Bishop and Queen, respectively.

Lion Dog, Great Elephant, and Teaching King

The Lion Dog, Great Elephant, and Teaching King can make up to three steps along any ray passing through them. They can return to, but not overshoot their starting squares. Each of the steps can be a move, a capture or a hop, with the exception that it cannot hop back to the starting square. So each of them can:

• move and capture as King, optionally taking out an enemy on the second square (2 steps out, 1 in, or jump 2 out, 1 step in)
• move or capture to the second square on any ray, optionally taking out an enemy on the square it passes over in the process
• move or capture to the third square on any ray, optionally taking out any enemies on the squares it passes over in the process
• capture a piece adjacent to it without moving
• pass a turn if there is an empty square next to it

The Great Elephant and Teaching King can in addition move as a normal Lion and Queen, respectively.

Free Eagle

The Free Eagle can move as a Queen, but as an alternative can make two diagonal steps, in independently chosen directions, even when this makes it return to its starting square. It can make the first step as jump, when it chooses to do so. So it can:

• Jump directly to the second square in any direction,
• Annihilate any opponent standing diagonally next to it, without moving (formally one step, and then a step back),
• Annihilate any opponent standing diagonally next to it, moving on to an empty square diagonally next to that ('hit and run'),
• Annihilate any opponent standing diagonally next to it, and normally capture an opponent standing diagonally next to that ('double capture'),
• Stay in place without capturing anything if one of the diagonally neighboring squares is empty (effectively passing a turn)

In other words, the Free Eagle is a Queen enhanced by the diagonal moves of a Lion.

Great Eagle and Great Falcon

The Great Eagle and Great Falcon move as Queen, and can jump to the second or third square before sliding in the same direction, except that in some directions they do not slide or jump and slide, but have a 'stinging' move, which can:

• move and capture on the first square, optionally taking out an enemy on the second square (2 steps out, 1 in, or jump 2 out, 1 step in)
• move or capture to the second square, optionally taking out an enemy on the square it passes over in the process
• move or capture to the third square, optionally taking out any enemies on the squares it passes over in the process
• capture a piece on the first square to it without moving
• pass a turn if the first square is empty

They can do any of this while capturing an opponent on the final square, or when moving to an empty square. The Great Falcon does this only straight forward, and the Great Eagle in the two diagonally forward directions.

Soaring Eagle and Horned Falcon

The Soaring Eagle and Horned Falcon move as Queen, except that in some directions they do not slide, but have a 'stinging' move, which can:

• Move to the first or jump to the second square,
• Jump to the second square, annihilating an opponent on the first square,
• Annihilate an opponent on the first square without moving (formally one step, and then a step back),
• When the first square is empty, move there and step back (effectively passing the turn).

They can do any of this while capturing an opponent on the final square, or when moving to an empty square. The Horned Falcon does this only straight forward, and the Soaring Eagle in the two diagonally forward directions.

Violent Falcon and Fierce Eagle

The Violent Falcon and Fierce Eagle move as Bishop and Rook, respectively. In addition, they can make a (1,2) leap in any direction.

Side Chariot and Vertical Chariot

The Side Chariot and Vertical Chariot slide sideways and vertically, respectively. In addition, they can step one square diagonally.

Free Wolf

The Free Wolf can slide sideways or move one square in any direction.

Lance

The Lance, in addition to sliding directly forward, can slide up to two squares directly backward.

Roaring Dog

The Roaring Dog can step one square in any direction. In addition, it can jump to the second square in any direction before optionally stepping one square in the same direction.

Poisonous Snake

The Poisonous Snake can step up to two square orthogonally, or one square diagonally forward.

Old Kite

The Old Kite can step up to two square diagonally, or one square sideways.

Flying Horse and Flying Dragon

The Flying Horse and Flying Dragon move up to two squares diagonally and orthogonally, respectively.

Tile General

The Tile General can step one square in any forward direction.

Pawn

The Pawn occurs in its Shogi form, moving as well as capturing one square directly forward.

Rules

Deciding who moves first

A furigoma (振り駒 piece toss) is used to decide who moves first. One of the players tosses five pawns. If the number of tokins (promoted pawns, と) facing up is higher than unpromoted Pawns (歩), then the player who tossed the pawns plays Gote (後手 White) (that is, getting the second move).

The players may also decide who goes first through a game of chance or a mutual agreement.

Sente (先手 Black) moves first, then players alternate making a move. Making a move is required – skipping a move is illegal, even when having to move is detrimental. Play continues until a player's last remaining royal piece is captured, a player resigns, or a draw is declared.

Skipping a turn

The Divine Spirit, Teaching King, Great Eagle, Great Falcon, Lion Hawk, Free Eagle, Great Elephant, Lion, Lion Dog, Soaring Eagle, and Horned Falcon can all skip a turn if at least one adjacent igui square is empty. However, it is illegal for a player to skip two consecutive turns. Note that if a piece promotes without moving, this does not count as skipping a turn.

Promotion

Whenever a piece captures something, it promotes. Promotion is indicated by turning the piece over after it moves, revealing the character of the promoted piece. Promotion is compulsory when possible; it is illegal to defer a promotion upon capturing, or promote without capturing.

The pieces promote as follows:

Because promotion doesn't happen until the end of the turn, multi-capturing pieces that promote have a chance to make a multi-capture.

The King, Hook Mover, and Tengu do not promote, nor can already promoted pieces promote further, with the following exception:

Any piece, promoted or not, that captures a Deva or Teaching King promotes to a Teaching King. This is effected by replacing it on the board with the captured piece. Similarly, any piece that captures a Dark Spirit or Divine Spirit promotes to a Divine Spirit. This is sometimes expressed as the piece being contagious: when something captures a contagious piece type, it becomes that piece type. Multi-capturing pieces that capture two different contagious pieces promote to the promoted form of the last contagious piece that they capture. The only exception to this is (potentially) royal pieces (Kings, Princes, and promotable Drunk Elephants) which promote to their normal promoted forms, or stay as they are if already promoted or non-promotable.

Check

When a player’s last remaining royal piece (a King or Prince) is under immediate attack by at least one enemy piece, it is in check. A player who's last remaining royal is in check is not required to remove the the check, but this is almost always the best option, since a player who has no more royal pieces on the board loses the game. If a player has both a King and a Prince in play, that player may sacrifice one of them. A check can be removed in one of three ways, depending on the situation:

• Blocking the check by placing a piece in between the royal piece and the attacking piece
• Capturing the attacking piece
• Moving to a safe square

The King and Prince need not move out of check, and can even move into check, though this is almost always a blunder. If it is not possible for a player who only has a King or a Prince to get out of check, that piece is checkmated and the game is effectively over.

Illegal Move

A player who makes an illegal move loses immediately. Illegal moves include:

• Making more than one move per turn
• Skipping two consecutive turns
• Moving a piece contrary to how its movements are defined

This rule may be relaxed in casual games, where a player can take back the illegal move and make a legal move.

End of the game

A player who captures the opponent's last remaining royal piece (a King or Prince) wins the game.

Checkmate and Stalemate

If a player’s last remaining royal piece is placed in check and there is no legal move that will resolve the check, the checking move is also checkmate, and effectively wins the game.

If a player’s last remaining royal piece is not in check but that player has no legal moves, the game is a stalemate. Stalemate, like checkmate, leads to a win for the stalemating player.

Resignation

At any point in the game, a player may resign and their opponent wins the game.

Draw

There are only two ways for a draw to occur - 千日手 sennichite (repetition) and impasse.

Repetition Draw 千日手 sennichite - If the same game position occurs four times with the same player to move, then the game ends in a draw, as long as the positions are not due to turn-skipping violations.

Impasse – If neither player can hope to force checkmate or stalemate on the other player’s last remaining royal piece or gain any further material through a series of legal moves, the players may agree to a draw.

Notes

Similar Games

• Shoko Shogi
• Suzumu Shogi
• Mitsugumi Shogi

Backstory

When I first came up with Hook Shogi, it was a 19x19 game that was actually a smaller version of a bigger game. During the development of Suzumu Shogi, Hook Shogi was the only large Shogi variant of mine that was largely immune to the design process thanks to the fact that it didn't have any of the pieces that were constantly changing. However, when the ups and downs in the design process came to a head, I deleted Hook Shogi and the rest of my large Shogi variants, and took a break from inventing chess variants. After a while, I revived this game, albiet in a smaller form with different pieces.

Thoughts on the Pieces

Because the hook moving pieces have such an enormous influence, it is really easy to trade them. This is especially true in games where they are close to the very front of the initial position, such as Maka Dai Dai Shogi. For example, in the video Maka Dai Dai Shogi - Two Nations March, both Black's Hook Mover and White's Capricorn are gone within the first three moves. This defeats the very purpose of the hook moving pieces, whose job is to serve as the power pieces of these games. As Eric Silverman has said in his article Powerful Pieces in Chess Games, power pieces (pieces which are much more powerful other pieces in the army) are important to a game's success. However, this problem can be solved quite easily by simply forbidding the hook moving pieces from capturing each other, which is what Tengu Dai Shogi does. Here, the rule is expanded to include all four hook moving pieces. This makes it much more likely that at least one will survive until the very end of the game.

The anti-trading rule for the hook moving pieces doesn't garauntee their survival though, as it only prevents direct trades involving one hook moving piece capturing another (HM x HM). Because of this, there is also a failsafe - the Deva and Dark Spirit. Their contagious promotions (to Teaching King and Divine Spirit, respectively) make them effectively immortal, ensuring that even when all hook moving pieces are gone, there will still be a power piece on the board. Normal trading (like TK x TK, any x TK) will not work, as the 'any' will promote to TK, so that the opponent gets its TK back, and you in fact traded your precious TK for an 'any'. Likewise, indirect trades (any x TK, any2 x TK) do not work, as now both any and any2 promote to TK, so that only any2 was traded for any, and both TK survive.

The Great Elephant moves like the Furious Fiend from the historical Shogi variants. I wanted to include the Furious Fiend's move (Lion + Lion Dog) in this game, but the Lion's promotion was already taken by the Lion Hawk, and in earlier versions of Hook Shogi I wanted to use the Great Elephant's move from the historical Shogi variants (Slide + Lion Dog move orthogonally, and diagonally backward, move one or two squares diagonally forward) for the Great Eagle, and a similar move for the Great Falcon. To solve this issue, I decided to give the Furious Fiend's move to the Great Elephant. When it turned out that the original moves for the Great Eagle and Great Falcon were a bit too powerful, I changed them to what they are now.

The Tile General is a bit weaker in this game, as it has the move of the Iron General from the historical Shogi variants. This was done to maintain consistency between Hook Shogi and my other large Shogi variants, where the Iron General moves like the Tile General from the historical Shogi variants.

Last revised by A. M. DeWitt.