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Shosu Shogi

Introduction

Shosu Shogi (小数将棋 shōsū shōgi, "decimal shogi") is a game I invented during my early inventing spree back in 2016. It is very similar to standard Shogi, but is played on a 10x10 board. Among the novelties in Shosu Shogi are the Queens, which have the combined powers of the Rook and Bishop, and Gold Generals with the ability to promote. In addition to this, the Lance and Knight have more powerful promoted forms than they do in standard 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 static images and the Mnemonic piece directory use H. G. Muller's Mnemonic pieces. However, this set is not the same as the one on his CVP article for that game because a few of the pieces have different moves, which was a difference I wanted to show in that diagram. The white Shogi pieces used in the diagram and the table in the Pieces section are my own pieces, made using a free online pixel art drawing tool called Pixilart. The tan Shogi pieces are from the Tenjiku Shogi Pieces set. They were made by an unknown author.

files=10 ranks=10 holdingsType=-1 promoOffset=8 promoZone=3 maxPromote=7 promoChoice=+ royal=16 graphicsDir=../membergraphics/MShanten-shogi/ whitePrefix=w1 blackPrefix=b1 lightShade=#FFFF80 darkShade=#FFFF80 graphicsType=png?nocache=true enableAI=0 squareSize=45 symmetry=rotate pawn:P:fW:p:a3,b3,c3,d3,e3,f3,g3,h3,i3,j3 bishop:B:B:b:b2 rook:R:R:r:i2 lance:L:fR:l:a1,j1 knight:N:ffN:n:b1,i1 silver general:S:FfW:s:c1,h1 gold general:G:WfF:g:d1,g1 queen:Q:Q:q:e1 tokin:+P:WfF:p2: dragon horse:+B:BW:b2: dragon king:+R:RF:r2: vertical mover:+L:WvR:l2: white horse:+N:N:n2: vice general:+S:WfF:s2: great general:+G:FfsW:g2: king:K:K:k:f1

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.

First Rank

  • Lances (10j, 1j)
  • Knights (9j, 2j)
  • Silver Generals (8j, 3j)
  • Gold Generals (7j, 4j)
  • Queen (6j)
  • King (5j)

Second Rank

  • Bishop (9i)
  • Rook (2i)

Third Rank

  • Pawns (10h, 9h, 8h, 7h, 6h, 5h, 4h, 3h, 2h, 1h)

Pieces

The following table shows the moves of the pieces. XBetza notation is included for easier reference.

Piece Promoted Piece


King

The King moves one space in any direction, but not into check. (K)

The King does not promote.


Queen

The Queen moves as it does in Chess - it slides orthogonally or diagonally. (Q)

The Queen does not promote.


Rook

The Rook moves as it does in Chess - it slides orthogonally. (R)



Dragon King

The Dragon King moves as it does in Shogi - it can move as a Rook or as a King. (RF)



Bishop

The Bishop moves as it does in Chess - it slides diagonally. (B)



Dragon Horse

The Dragon Horse moves as it does in Shogi - it can move as a Bishop or as a King. (BW)



Gold General

The Gold General moves as it does in Shogi - it moves one square orthogonally or diagonally forward. (WfF)



Great General

The Great General moves one square diagonally, sideways, or directly forward. (FfsW)



Silver General

The Silver General moves as it does in Shogi - it moves one square diagonally or directly forward. (FfW)



Vice General

The Vice General moves as a Gold General. (WfF)



Knight

The Knight moves as it does in Shogi - it jumps two squares forward and one square sideways. (ffN)



White Horse

The White Horse moves the Knight in Chess - it jumps to the nearest square that a Queen cannot. (N)



Lance

The Lance slides directly forward. (fR)



Vertical Mover

The Vertical Mover can slide vertically or move one square sideways. (WvR)



Pawn

The Pawn moves as it does in Shogi - one square orthogonally forward. (fW)



Tokin

The Tokin moves as it does in Shogi - it moves one square orthogonally or diagonally forward. (WfF)

Rules

Promotion

When a piece moves to, from, or within the owner’s promotion zone, the owner may promote that piece. The promotion zone is the last three ranks of the board - the three ranks occupied by the opponent’s pieces at the start of the game. Promotion is optional – a player need not promote a piece immediately upon entering the promotion zone. However, a piece must promote if it would otherwise have no legal moves left on a subsequent turn. The promotions for each piece are as follows.

Rook => Dragon King

Bishop => Dragon Horse

Gold General => Great General

Silver General => Vice General

Knight => White Horse

Lance => Vertical Mover

Pawn => Tokin

A promoted piece that get captured reverts to its unpromoted state. Otherwise, a promotion is permanent. Promoted pieces cannot be demoted in any other way. Pieces can only promote once – promoted pieces cannot promote any further. The King and Queen do not promote.

Lances, Knights, and Pawns

If a Lance, Knight, or Pawn reaches the last rank, it must promote because it would otherwise have no legal moves left on a subsequent turn. A Knight that reaches the penultimate rank must promote for the exact same reason.

Drops

Captured pieces get retained in hand and can be brought back into play under the capturing player’s control. On any turn, instead of moving a piece on the board, a player may return a captured piece to any empty square on the board. This is called dropping the piece, or simply a drop. A drop counts as a complete move. The rules regarding drops are as follows.

  • A piece may not be dropped onto an occupied space.
  • Pieces that are dropped within the promotion zone do not promote immediately.
  • A piece may not be dropped onto a space where it would have no legal moves left on a subsequent turn.

Captures and promotions may occur normally on a subsequent move of the piece.

Lances and Knights

Lances and Knights may not be dropped onto the last rank, as they would have no legal moves left. Knights may not be dropped onto the penultimate rank for the exact same reason.

Pawns

In addition to the rules mentioned above, there are special rules concerning pawn drops.

  • Two Pawns (Japanese: 二歩 nifu): A Pawn cannot be dropped on a file that already contains an unpromoted Pawn belonging to the same player (promoted pawns do not count).
  • Drop Pawn Mate (Japanese: 打ち歩詰め uchifudzume): A Pawn cannot be dropped to give immediate checkmate (although other pieces may be dropped to give immediate checkmate). A Pawn may, however, be dropped to give immediate check as long as it is not also checkmate. A Pawn may also be dropped to give immediate stalemate. This rule does not apply to Pawns that are already on the board.

Check, Checkmate, and Stalemate

When a King is threatened with capture on the next turn, it is in check. A King that is in check must immediately get out of check. This can be done in one of three ways, depending on the situation:

  • Moving the King to a safe square
  • Blocking the check
  • Capturing the attacking piece

If the king is in check and cannot escape capture, it is in checkmate. Checkmate counts as a loss for the checkmated player. If a player's king is not in check but has no legal moves, it is in stalemate. The result of a stalemate is the same as that of checkmate – it is a loss for the stalemated player.

Illegal Move

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

  • Violating the Two Pawns (nifu) restriction
  • Violating the Drop Pawn Mate (uchifuzume) restriction
  • Dropping or moving a piece to position where it cannot move
  • Making more than one move per turn
  • Moving one's king into check
  • Moving a piece contrary to how its movements are defined

Repetition Draw 千日手 sennichite - If the same game position occurs four times with the same player to move and the same pieces in hand for each player, then the game ends in a draw.

Impasse - If both kings have advanced into their respective promotion zones and neither player can hope to mate the other or to gain any further material, the players may agree to a draw.

Notes

The Queen and White Horse may also be labelled 妃将 (okisaki, meaning queen general in Japanese) and 跳馬 (chōma, meaning jumping horse in Japanese), respectively.

The White Horse's Japanese name, 白馬 (hakuba), translates to "white horse". This should not be confused with the White Horse from Chu Shogi, whose Japanese name, 白駒 (hakuku), actually translates to "white piece".

Computer Play

You can Play Shosu Shogi online with Game Courier.



This 'user submitted' page is a collaboration between the posting user and the Chess Variant Pages. Registered contributors to the Chess Variant Pages have the ability to post their own works, subject to review and editing by the Chess Variant Pages Editorial Staff.


By Adam DeWitt.
Web page created: 2019-01-04. Web page last updated: 2020-07-05