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Dai Shogi

Introduction

Dai Shogi is a precursor of Chu Shogi. The latter was the most popular form of Chess in Japan for many centuries. Compared to Chu Shogi, Dai Shogi has 16 extra pieces of 8 types, which all promote to Gold General. It also lacks the refined rules against Lion trading.

The extra pieces are rather weak, and promote to the also weak Gold General. As a result of this, and due to the longer time it takes the many steppers to cross the larger board, Dai Shogi is a much slower game than Chu. It is thus not surprising the latter quickly surpassed Dai Shogi in popularity.

Setup

First rank

  • a1, o1 Lance (fR)
  • b1, n1 Knight (ffN)
  • c1, m1 Stone General (fF)
  • d1, l1 Iron General (fFfW)
  • e1, k1 Copper General (fFvW)
  • f1, j1 Silver General (FfW)
  • g1, i1 Gold General (WfF)
  • h1 King (royal K)

Fourth rank

  • a4, o4 Rook (R)
  • b4, n4 Flying Dragon (F2)
  • c4, m4 Side Mover (sRvW)
  • d4, l4 Vertical Mover (vRsW)
  • e4, k4 Bishop (B)
  • f4, j4 Dragon Horse (BW)
  • g4, i4 Dragon King (RF)
  • h4 Free King (Q)

Fifth and sixth rank

  • a5-o5 Pawns (fW)
  • e5, k5 Go Between (vW)

Second rank

  • a2, o2 Reverse Chariot (vR)
  • c2, m2 Cat Sword (F)
  • e2, k2 Ferocious Leopard (FvW)
  • g2, i2 Blind Tiger (FbsW)
  • h2 Drunk Elephant (FfsW)

Third rank

  • b3, n3 Violent Ox (W2)
  • d3, l3 Angry Boar (W)
  • f3, j3 Evil Wolf (fFfsW)
  • g3 Kirin (FD)
  • h3 Lion (KNAD(cK-aK)(mK-bK)
  • i3 Phoenix (WA)

Pieces

Lion

The Lion is a double mover: it can make upto 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 jump, when it choose to do so. So it 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)

Soaring Eagle, Horned Falcon

Eagle and 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, the Soaring Eagle in the two diagonally forward directions.

Knight and Pawn

The Knight and Pawn occur in the Shogi version, the Knight having only is two forward-most moves, and the Pawn both moving and capturing straight ahead.

Rules

Goal

The game is won by eliminating the opponent's royal piece(s). Royal are King and 'Prince', the latter being a second King obtainable through promotion. There is no rule against venturing into or leaving yourself in check, although this would of course be unwise. This makes stalemate non-existent in real games, and if there ever has been a rule for it, it is no longer known. For definiteness we can assume that stalemate is a win.

Promotion

Like in most Shogi variants, it is not just the Pawns that can promote, but almost all pieces. There is no choice for what to promote to: each piece type has a pre-determined promoted form (written on the back of the tile used to represent the piece, so that it can be flipped to perform the promotion). They often promote to a piece that was already present in the initial setup. But in that case it cannot promote again, even if the latter does: every piece promotes at most once. So a Rook obtained by promoting a Gold is really a different Rook from the one present initially, as the latter can still promote, and is thus much more valuable.

Pieces can promote when they enter the promotion zone formed by the furthest four board ranks. This is optional; you can always defer promotion, and in some cases that makes sense, because not all promoted pieces are strictly upward compatible with their unpromoted forms. In addition, moves that start inside the promotion zone can lead to promotion when they capture something.

Pieces promote as follows (moves only indicated for pieces not occurring in the initial setup):

  • Kirin -> Lion
  • Phoenix -> Free King
  • Dragon King -> Soaring Eagle
  • Rook -> Dragon King
  • Gold General -> Rook
  • Pawn -> Gold
  • Dragon Horse -> Horned Falcon
  • Bishop -> Dragon Horse
  • Ferocious Leopard -> Bishop
  • Vertical Mover -> Flying Ox (BvR)
  • Silver General -> Vertical Mover
  • Lance -> White Horse (vRfB)
  • Reverse Chariot -> Whale (vRbB)
  • Blind Tiger -> Flying Stag (vRFsW)
  • Drunk Elephant -> Crown Prince (royal K)
  • Go Between -> Drunk Elephant
  • Side Mover -> Free Boar (BsR)
  • Copper General -> Side Mover
  • Stone General -> Gold General
  • Iron General -> Gold General
  • Knight -> Gold General
  • Angry Boar -> Gold General
  • Cat Sword -> Gold General
  • Evil Wolf -> Gold General
  • Violent Ox -> Gold General
  • Flying Dragon -> Gold General

One army with all pieces promoted
King, Lion and Queen do not promote, and thus from a game-theoretical point of view are identical to promoted Elephant, promoted Kirin and promoted Phoenix.

Crown Prince

The Elephant promotes to Crown Prince, which is just another name for King. So you can have two royals in Dai Shogi. This counts as extinction royalty, i.e. when you have two royals, one of them can be captured without ill effects, and only when your last royal is captured you lose the game.

Repetitions

The historic sources mention that repetition is forbidden, but do not elaborate on which side carries the burden to avoid it. It is likely that you could not win by perpetually checking your opponent, and that the burden to deviate was thus upon the checker, like in all Asian variants. The modern interpretation of this rule is that evading a perpetual chase, with moves that do not attack anythinging should also be always allowed, so that the chaser must deviate, and that repeats reached without either side attacking anything should be draws.

Notes

'Dai' means 'large', and 'chu' means middle, so Dai Shogi must obviously be older than Chu Shogi, or the latter would not have been called 'middle'. It seems that Chu Shogi was derived from Dai Shogi as an attempt to speed up the game by removing the slowest pieces that also had weak promotions.

It is intriguing that the eliminated pieces all promote to Tokin, while in Chu Shogi all pieces promote differently, and the Tokin only appears as promoted Pawn. This makes one wonder if there is not a form of 'back contamination' here. Like that originally in Dai Shogi all the generals promoted to Gold (as Silver and Knight do in Sho Shogi), and that after elimination of the weakest pieces to produce Chu Shogi, Copper, Silver, Gold and Leopard were still considered too insignificant, and were assigned new promotions to pieces in the initial setup that could not yet be promoted to. And that these promotions then later trickled back into Dai Shogi, when people got accustomed to them. This is pure speculation, however.



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Author: H. G. Muller.
Web page created: 2015-04-20. Web page last updated: 2015-04-20