Tai shogi


Tai shogi is a large-board variant of shogi. The game dates to the 15th century and is based on earlier large-board shogi games. Before the discovery of taikyoku shogi in 1997, tai shogi was believed to be the largest playable chess variant, if not board game, ever. One game may be played over several long sessions and require each player to make over a thousand moves. It was never a popular game; indeed, a single production of six game sets in the early 17th century was a notable event.
Like other large-board variants, but unlike standard shogi, the game is played without drops, and uses a promotion-by-capture rule.
Because of the terse and often incomplete wording of the historical sources for the large shogi variants, except for chu shogi and to a lesser extent dai shogi, the historical rules of tai shogi are not clear. Different sources often differ significantly in the moves attributed to the pieces, and the degree of contradiction is such that it is likely impossible to reconstruct the "true historical rules" with any degree of certainty, if there ever was such a thing. It is not clear if the game was ever played much historically, as the few sets that were made seem to have been intended only for display.

Rules of the game

Tai shogi is very similar to other large-board shogi variants: dai dai shogi, maka dai dai shogi, and tenjiku shogi. Where the same pieces are found, they move the same way. The only difference is in how these pieces promote, which is distinct for each shogi variant. The one variant which is an exception to this generalization is the largest, taikyoku shogi, where the moves differ as well.

Objective

The objective of the game is to capture the opponent's emperor and prince. When the last of these is captured, the game ends. There are no rules for check or checkmate; however, in practice a player resigns when checkmated.

Game equipment

Two players, Black and White, play on a board ruled into a grid of 25 ranks and 25 files, for a total of 625 squares. The squares are undifferentiated by marking or color.
Each player has a set of 177 wedge-shaped pieces of 93 types. In all, the players must remember 99 moves for these pieces. The pieces are of slightly different sizes. From largest to smallest they are:
Several of the English names were chosen to correspond to rough equivalents in Western chess, rather than as translations of the Japanese names.
Each piece has its name in the form of two kanji written on its face. On the reverse side of some pieces are one or two other characters, often in a different color ; this reverse side is turned up to indicate that the piece has been promoted during play. The pieces of the two sides do not differ in color, but instead each piece is shaped like a wedge, and faces forward, toward the opposing side. This shows who controls the piece during play.

Table of pieces

Listed here are the pieces of the game and, if they promote, which pieces they promote to.
Piece KanjiRōmajiPromotes to
Emperor天王 tennō
Prince太子taishi
Hook mover鉤行kōgyōG
Long-nosed goblin天狗tenguG
Capricorn*摩?makatsuG
Peacock孔雀kujakuG
Soaring eagle飛鷲hijūG
Horned falcon角鷹kakuōG
Queen奔王honnō
Rushing bird行鳥††gyōchōfree demon ††
Free demon 奔鬼honkiG
Free dream-eater 奔獏honbakuG
Water buffalo水牛suigyūfree dream-eater
Flying ox飛牛higyūG
Soldier兵士heishiG
Dragon king龍王ryūō
Dragon horse龍馬ryūme
Lion獅子shishifurious fiend
*Furious fiend奮迅funjin
Side chariot走車sōshaG
Rook飛車hishaG
Bishop角行kakugyōG
White horse白駒hokkuG
Whale鯨鯢keigeiG
Standard bearer前旗zenkiG
Vermillion sparrow朱雀suzakuG
Turtle-snake玄武genbuG
Blue dragon青龍seiryūG
White tiger白虎byakkoG
Right chariot右車ushaG
Left chariot左車sashaG
Side dragon横龍ōryūG
Dove鳩槃kyūhanG
She-devil夜叉yashaG
Golden bird金翅kinshiG
Great dragon大龍dairyūG
White elephant白象hakuzōG
Lion dog狛犬komainuG
*Great elephant大象taizō
Wrestler力士rikishiG
Guardian of the Gods金剛kongōG
Buddhist devil羅刹rasetsuG
Golden deer金鹿konrokuG
Silver hare銀兎gintoG
Fierce eagle猛鷲mōjūG
Old kite古鵄kotetsulong-nosed goblin
Violent ox猛牛mōgyūG
Flying dragon飛龍hiryūG
Old rat老鼠rōsobat
*Bat蝙蝠kōmori
Enchanted badger変狸henridove
Flying horse馬麟barinqueen
Prancing stag踊鹿yōrokusquare mover
*Square mover方行hōgyō
Violent bear猛熊mōyūG
Side mover横行ōgyōG
Vertical mover竪行shugyōG
Reverse chariot反車henshaG
Phoenix鳳凰hōōgolden bird
Kirin麒麟kiringreat dragon
Poisonous snake毒蛇dokujahook mover
Northern barbarian北狄hokutekifragrant elephant **
*Fragrant elephant香象kōzō— **
Southern barbarian南蛮nanbanwhite elephant **
Eastern barbarian東夷tōilion
Western barbarian西戎seijūlion dog
Blind bear盲熊mōyū奔熊 honyū Free bear
Drunken elephant醉象suizōprince
Neighboring king近王kinnōstandard bearer
Blind tiger盲虎mōko奔虎 honko Free tiger ※
Blind monkey盲猿mōenG
Ferocious leopard猛豹mōhyō奔豹 honpyō Free leopard ※
Reclining dragon臥龍garyū奔龍 honryū Free dragon ※
Chinese cock淮鶏waikeiwizard stork
*Wizard stork*仙鶴senkaku
Old monkey古猿koenmountain witch
*Mountain witch山母sambo
Evil wolf悪狼akurō奔狼 honrō Free wolf ※
Angry boar嗔猪shincho奔猪 honcho Free boar
Cat sword猫刄myōjin奔猫 honmyō Free cat ※
Coiled serpent蟠蛇banja奔蛇 honja Free snake ※
Deva提婆daibateaching king
*Teaching king教王kyōō
Dark spirit無明mumyōBuddhist spirit
*Buddhist spirit法性hōsei
Right general右将ushōG
Left general左将sashōG
Gold general金将kinshō奔金 honkin Free gold ※
Silver general銀将ginshō奔銀 hongin Free silver ※
Copper general銅将dōshō奔銅 hondō Free copper ※
Tile general瓦将gashō奔瓦 honga Free tile ※
Iron general鉄将tesshō奔鉄 hontetsu Free iron ※
Wood general木将mokushōG
Stone general石将sekishō奔石 honseki Free stone ※
Earth general土将doshō奔土 hondo Free earth ※
Go-between仲人chūnin奔人 honnin Free go-between ※
Knight桂馬keimaG
Howling dog*?犬kikenG
Donkey驢馬robaG
Ram's-head soldier羊兵yōheiG
Lance香車kyōshaG
Pawn歩兵fuhyōG

Setup

Below is a diagram showing the setup of one player's pieces. The way one player sees their own pieces is the same way the opposing player will see their pieces.
GB GB
PPPPPPPPPPPPPPPPPPPPPPPPP
HDFHENDOFOSMVMVBSBPRABEWLDEWABPRSBVBVMSMFODOENFHHD
LCBDWOEASGTICORCORDCADEHMRDCOORCITSGEAWOVSRC
SOWBFLWSEBCCHFOMOKPCGDKRLNPHGOPCRBOMHFCCSUNBFLWBSO
SCWHRSVOCSBBSVGLBMBTBUWRNKGGSDBTBMGLSVBBCSVORSWHSC
RVSISENPSFTBFEWEFRSLGCPRGSFRWEFEBFTPSNSESIRV
LTSWFDLODRDHDKQGDVEDSGQDKDHRDLOFDWWTL

AB - Angry BoarB - BishopBB - Blind BearBD - Blue Dragon
BU - Buddhist DevilBM - Blind MonkeyBT - Blind TigerC - Copp. General
CA - CapricornCC - Chinese CockCO - Coiled SerpentCP - Prince
CS - Cat SwordD - DoveDE - Drunken ElephantDH - Dragon Horse
DK - Dragon KingDO - DonkeyDS - Dark SpiritDV - Deva
E - EmperorEA - Earth GeneralEB - Eastern BarbarianEN - Enchanted Badger
EW - Evil WolfFD - Flying DragonFE - Fierce EagleFH - Flying Horse
FL - Fer. LeopardFO - Flying OxFR - Free DemonFT - Free Dream-Eater
G - Gold GeneralGB - Go BetweenGD - Great DragonGG - Guardian of the Gods
GL - Golden DeerGO - Golden BirdHD - Howling DogHF - Horned Falcon
HM - Hook MoverI - Iron GeneralKR - KirinL - Lance
LC - Left ChariotLD - Lion DogLG - Left GeneralLN - Lion
LO - Long-nosed GoblinN - KnightNB - Northern BarbarianNK - Neighbor King
OK - Old KiteOM - Old MonkeyOR - Old RatP - Pawn
PC - PeacockPH - PhoenixPR - Prancing StagPS - Poison Snake
Q - QueenR - RookRB - Rushing BirdRC - Right Chariot
RD - Reclining DragonRG - Right GeneralRS - Ram's-head SoldierRV - Reverse Chariot
S - Silver GeneralSB - Standard BearerSC - Side ChariotSD - She-devil
SE - Soaring EagleSG - Stone GeneralSI - Side DragonSM - Side Mover
SO - SoldierSU - Southern BarbarianSV - Silver HareT - Tile General
TS - Turtle-snakeVB - Violent BearVM - Vert. MoverVO - Violent Ox
VS - Vermillion SparrowW - WhaleWB - Water BuffaloWE - White Elephant
WH - White HorseWO - Wood GeneralWR - WrestlerWS - Western Barbarian
WT - White Tiger

Game play

The players alternate making a move, with Black moving first. A move consists of moving a single piece on the board and potentially promoting that piece or displacing an opposing piece. Each of these options is detailed below.

Movement and capture

When the same piece occurs in tai shogi and maka dai dai shogi, it moves and promotes the same way in both.
An opposing piece is captured by displacement: That is, if a piece moves to a square occupied by an opposing piece, the opposing piece is displaced and removed from the board. A piece cannot move to a square occupied by a friendly piece.
Each piece on the game moves in a characteristic pattern. Pieces move either orthogonally, or diagonally. The emperor, lion, and knight are exceptions at the beginning of the game, in that they do not move, or are not required to move, in a straight line.
If a piece that cannot retreat or move aside advances across the board until it can no longer move, it must remain there until captured. This applies to the pawn, lance, ram's-head soldier, stone general, wood general, and iron general upon reaching the farthest rank, and to the knight upon reaching either of the two farthest ranks.
Many pieces are capable of several kinds of movement, with the type of movement most often depending on the direction in which they move. The movement categories are:

Step movers

Some pieces move only one square at a time.
The step movers are the prince, drunk elephant, neighbor king, blind tiger, blind monkey, ferocious leopard, reclining dragon, Chinese cock, old monkey, evil wolf, the generals, angry boar, cat sword, coiled serpent, deva, dark spirit, go between, and the 25 pawns on each side.

Limited ranging pieces

Some pieces can move along a limited number of free squares along a straight line in certain directions. Other than the limited distance, they move like ranging pieces.
These pieces are the water buffalo, standard bearer, vermillion sparrow, turtle-snake, blue dragon, white tiger, dove, she-devil, golden bird, great dragon, white elephant, lion dog, wrestler, Guardian of the Gods, Buddhist devil, golden deer, silver hare, fierce eagle, old kite, violent ox, flying dragon, old rat, enchanted badger, flying horse, prancing stag, violent bear, the barbarians, and the wood general.

Jumping pieces

Several pieces can jump, that is, they can pass over any intervening piece, whether friend or foe, with no effect on either. These are the lion, kirin, phoenix, poison snake, donkey, and knight.

Ranging pieces

Many pieces can move any number of empty squares along a straight line, limited only by the edge of the board. If an opposing piece intervenes, it may be captured by moving to that square and removing it from the board. A ranging piece must stop where it captures, and cannot bypass a piece that is in its way. If a friendly piece intervenes, the moving piece is limited to a distance that stops short of the intervening piece; if the friendly piece is adjacent, it cannot move in that direction at all.
The ranging pieces are the soaring eagle, horned falcon, queen, rushing bird, the demons, free dream-eater, water buffalo, flying ox, soldier, dragon king, dragon horse, the chariots, rook, bishop, white horse, whale, standard bearer, vermillion sparrow, turtle-snake, blue dragon, white tiger, side dragon, golden bird, great dragon, white elephant, golden deer, movers, howling dog, ram's-head solder and lance.

Hook moves (changing tack)

The hook mover, long-nosed goblin, Capricorn, and peacock can move any number of squares along a straight line, as a normal ranging piece, but may also abruptly change tack left or right by 90° at any one place along the route, and then continue as a ranging piece. Turning a corner like this is optional.
The range covered by a hook move is the equivalent of two moves by a rook, or two moves by a bishop, depending the piece. However, a hook move is functionally a single move: The piece cannot capture twice in one move, nor may it capture and then move on. It must stop before an intervening piece, and must stop when it captures, just like any other ranging piece. It can only change direction once per move.

Lion moves (multiple captures)

The lion, lion dog, soaring eagle, and horned falcon have sequential multiple-capture abilities, called "lion moves". Among the pieces that only appear with promotion, so do the teaching king, buddhist spirit, and furious fiend. The details of these powerful moves are described for the lion, below.

Individual pieces

When a piece occurs in both tai shogi and maka dai dai shogi, it moves and promotes the same way. Betza's funny notation has been included in brackets for easier reference, with the extension that the notation xxxayyyK stands for an xxxK move followed by an yyyK move, not necessarily in the same direction. Larger numbers of 'legs' can be indicated by repeated application of 'a'. Directional modifiers on continuation legs must be interpreted relative to the previous leg, where 'f' means 'continue in the same direction'; default is 'all directions'. The default modality of the final leg is the usual 'mc', but on non-final legs also includes a hop over an obstacle at their end-point, provided the path does not bend back onto itself there. Other modalities must be written explicitly. U denotes the universal leaper, a piece which can jump to any square on the board except the one that it is on.
Emperor 天王 tennō

Prince 太子 taishi
Hook mover 鉤行 kōgyō
Long-nosed goblin 天狗 tengu
Capricorn 摩? makatsu
Peacock 孔雀 kujaku
Soaring eagle 飛鷲 hijū
Horned falcon 角鷹 kakuō
Queen 奔王 honnō
Rushing bird 行鳥 gyōchō
Free demon 奔鬼 honki
Free dream-eater 奔獏 honbaku
Water buffalo 水牛 suigyū
Flying Ox 飛牛 higyū
Soldier 兵士 heishi
Dragon king 龍王 ryūō
Dragon horse 龍馬 ryūme
Side chariot 走車 sōsha
Rook 飛車 hisha
Bishop 角行 kakugyō
Lion 獅子 shishi
White horse 白駒 hokku
Whale 鯨鯢 keigei
Standard bearer 前旗 zenki
Vermillion sparrow 朱雀 suzaku
There are two completely different claims for the movement of the sparrow.
Turtle-snake 玄武 genbu
There are two different movement options claimed for the turtle-snake:
Blue dragon 青龍 seiryū
White tiger 白虎 byakko
Right chariot 右車 usha
Left chariot 左車 sasha
Side dragon 横龍 ōryū
Dove 鳩槃 kyūhan
She-devil 夜叉 yasha
Golden bird 金翅 kinshi
Great dragon 大龍 dairyū
There are two descriptions of the move of this piece. The main Japanese Wikipedia entry gives it as,


However, a second description is found in the kirin article, as the kirin promotes to great dragon. In that description, the piece moves as described in dai dai shogi: no jumps to the side, and three steps in any of the four diagonals.
White elephant 白象 hakuzō
Lion dog 狛犬 komainu
Wrestler 力士 rikishi
Guardian of the Gods 金剛 kongō
Buddhist devil 羅刹 rasetsu
Golden deer 金鹿 konroku
Silver hare 銀兎 ginto
Fierce eagle 猛鷲 mōjū
Old kite 古鵄 kotetsu
Violent ox 猛牛 mōgyū
Flying dragon 飛龍 hiryū
Old rat 老鼠 rōso
Enchanted badger 変狸 henri
Flying horse 馬麟 barin
Prancing stag 踊鹿 yōroku
Violent bear 猛熊 mōyū
Side mover 横行 ōgyō
Vertical mover 竪行 shugyō
Phoenix 鳳凰 hōō
Kirin 麒麟 kirin
Reverse chariot 反車 hensha
Poisonous snake 毒蛇 dokuja
There are two different movement options claimed for the poison snake:
The Japanese site only explicitly makes this claim for dai dai shogi and taikyoku shogi. The move and promotion is symmetrical with the old kite in tai shogi, and one would expect the move to be different in these three game variants.
Northern barbarian 北狄 hokuteki
Southern barbarian 南蛮 namban
Eastern barbarian 東夷 tōi
Western barbarian 西戎 seijū
Blind bear 盲熊 mōyū
Drunk elephant 醉象 suizō
Neighbor king 近王 kinnō
Blind tiger 盲虎 mōko
Free tiger 奔虎 honko
Blind monkey 盲猿 mōen
Ferocious leopard 猛豹 mōhyō
Free leopard 奔豹 honpyō
Reclining dragon 臥龍 garyū
Free dragon 奔龍 honryū
Chinese cock 淮鶏 waikei
Old monkey 古猿 koen
Evil wolf 悪狼 akurō
Free wolf 奔狼 honrō
Angry boar 嗔猪 shincho
Cat sword 猫刄 myōjin
Free cat 奔猫 honmyō
Coiled serpent 蟠蛇 banja
Free serpent 奔蛇 honja
Dark spirit 無明 mumyō
The dark spirit has asymmetric options for movement.
Deva 提婆 daiba
The deva has asymmetric options for movement.
Right general 右将 ushō
Left general 左将 sashō
Gold general 金将 kinshō
Free gold 奔金 honkin
Silver general 銀将 ginshō
Free silver 奔銀 hongin
Copper general 銅将 dōshō
Free copper 奔銅 hondō
Tile general 瓦将 gashō
Free tile 奔瓦 honga
Iron general 鉄将 tesshō
Free iron 奔鉄 hontetsu
Wood general 木将 mokushō
Stone general 石将 sekishō
Free stone 奔石 honseki
Earth general 土将 doshō and go-between 仲人 chūnin
Free earth 奔土 hondo and free goer 奔人 honnin
Knight 桂馬 keima
Howling Dog ?犬 kiken
Donkey 驢馬 roba
Ram's-head soldier 羊兵 yōhei
Lance 香車 kyōsha
Pawn 歩兵 fuhyō
When a piece first makes a capture, it promotes. Promotion has the effect of changing how a piece moves. See the table above for what each piece promotes to. Promotion is effected by turning the piece over after it moves, revealing the name of its promoted rank. Promotion is both compulsory and permanent. Often "demotion" would be a better word, for most powerful pieces 'promote' to a gold general, which is a weak piece. It is the weaker pieces that tend to become more powerful upon making a capture.
This means that a player only gets to attack or defend with many of the original lion and hook movers once each before they lose their powers. To permanently gain such ability, certain weaker pieces must be promoted.
This is all very different from smaller shogi variants, where pieces promote when they cross a promotion zone, and where promotion is optional and usually a good thing. The dots on the tai shogi board that would represent promotion zones in other games are only there as placement guides for the initial setup of the two camps.
Some pieces promote, or demote, to a piece that exists in the initial setup of the board. However, such a piece cannot then promote a second time as its namesake does. For example, a gold general promotes to a free gold. However, while a hook mover demotes to a gold general on its first capturing move, it does not promote to a free gold on its second. Rather, it remains a gold general for the rest of the game. This should be clear from the game equipment, for each piece only has two sides.
Many of the step movers promote to free-ranging pieces but retain their directions of movement. These were listed above after the unpromoted pieces. Other pieces only appear as a result of promotion. They are as follows:

Pieces that only appear with promotion

These are in addition to the 'free' pieces mentioned in the previous section.
Teaching king 教王 kyōō
Buddhist spirit 法性 hōsei
Furious fiend 奮迅 funjin
Wizard stork 仙鶴 senkaku
Mountain witch 山母 sambo
Square mover 方行 hōgyō
Fragrant elephant 香象 kōzō
Great elephant 大象 taizō
Free bear 奔熊 honyū
Free boar 奔猪 honcho
Bat 蝙蝠 kōmori
When a player makes a move, such that the opponent's sole remaining emperor or prince could be captured on the following move, the move is said to give check to the emperor or prince; the emperor or prince is said to be in check. If a player's last emperor or prince is in check and no legal move by that player will get it out of check, the checking move is also mate, and effectively wins the game.
Unlike Western chess, a player need not move out of check, and indeed may even move into check. Although obviously not often a good idea, a player with more than one royal may occasionally sacrifice one of these pieces as part of a gambit.
A player is not allowed to give perpetual check to the sole objective piece.

Game end

A player who captures the opponent's sole remaining emperor or prince wins the game. In practice this rarely happens, as a player will resign when checkmated, as otherwise when loss is inevitable.
A player who makes an illegal move loses immediately.
Another possible, if rather uncommon, way for a game to end is repetition. If the same position occurs four times with the same player to play, then the game is no contest. Recall, however, the prohibition against perpetual check.

Game notation

The method used in English-language texts to express shogi moves was established by George Hodges in 1976. It is derived from the algebraic notation used for chess, but differs in several respects. Modifications have been made for tai shogi.
A typical example is P-8h.
The first letter represents the piece moved.
Promoted pieces have a + added in front of the letter.. The designation of the piece is followed by a symbol indicating the type of move: - for an ordinary move or x for a capture. Next is the designation for the square on which the piece lands. This consists of a number representing the file and a lowercase letter representing the rank, with 1a being the top right corner and 25y being the bottom left corner.
If a soaring eagle, horned falcon, lion or Buddhist spirit captures by 'igui’, the square of the piece being captured is used instead of the destination square, and this is preceded by the symbol '!'. If a double capture is made, then it is added after the first capture.
If a capture mandates the player to promote the piece, then a + is added to the end to signify that the promotion was taken. For example, ORx7c+ indicates an old rat capturing on 7c and promoting.
In cases where the above notation would be ambiguous, the designation of the start square is added after the designation for the piece in order to make clear which piece is meant.
Moves are commonly numbered as in chess.

Strategy

Piece values

According to the German Chu Shogi Association, the average values of the pieces are :
Piece nameApproximate valuePromotionApproximate value
Emperor
PrinceEmperor
Drunk ElephantPrince
Long-Nosed Goblin89
Peacock66
Hook MoverGold General
Capricorn88Gold General
Lion22Furious Fiend24
Queen21
Rushing Bird20Free Demon18
Free Dream-Eater19
Horned Falcon18
Free Demon18
Water Buffalo17Free Dream-Eater19
Soaring Eagle17
Flying Ox16
Standard Bearer15
Soldier14
Vermillion Sparrow13
White Horse13
Golden Bird12
White Tiger11
Blue Dragon11
Great Dragon11
Turtle Snake10
Left Chariot10
Right Chariot10
Dove
Whale
Lion DogGreat Elephant
White Elephant
Dragon King13
Dragon Horse12
Side Chariot12
Golden Deer
Ram's-Head Soldier
Silver Hare
She-DevilGold General
Guardian of the GodsGold General
WrestlerGold General
Buddhist DevilGold General
Rook11Gold General
Bishop10Gold General
Side Dragon10Gold General
Vertical MoverGold General
Side MoverGold General
Reverse ChariotGold General
Howling DogGold General
LanceGold General
Old KiteLong-Nosed Goblin89
Poisonous SnakeHook Mover
Eastern BarbarianLion22
Dark SpiritBuddhist Spirit35
DevaTeaching King29
Flying HorseQueen21
Neighbouring KingStandard-Bearer15
Old RatBat15
Chinese CockWizard Stork15
Northern BarbarianFragrant Elephant12
PhoenixGolden Bird12
Blind MonkeyMountain Witch12
KirinGreat Dragon11
Western BarbarianLion Dog
Southern BarbarianWhite Elephant
Enchanted BadgerDove
Prancing StagSquare Mover12
Flying DragonGold General
DonkeyGold General
KnightGold General
Fierce Eagle
Blind Bear
Left General
Right General
Blind Tiger
Violent Ox
Gold General
Ferocious Leopard
Violent Bear
Evil Wolf
Reclining Dragon
Silver General
Old Monkey
Copper General
Wood General
Iron General
Cat Sword
Coiled Serpent
Angry Boar
Tile General
Stone General
Earth General
Go-Between
Pawn

These average values do not take into account the special status of the prince as a royal piece, or emperor as disposable if there's a prince and other piece. They have also been normalized so that the pawn is worth 1 point to avoid fractions. Additionally, pieces change value if they have a good chance of promotion. This is particularly significant for the hook mover and capricorn, which are two of the most powerful pieces in the game, but "promote" to the weak gold general; and the old kite and poisonous snake, which promote respectively to the hook mover and long-nosed goblin.