Tai shogi

Tai shogi (泰将棋 "tai shōgi" or 無上泰将棋 "mujō tai shōgi" "grand chess", renamed from 無上大将棋 "mujō dai shōgi" "supreme chess" to avoid confusion with 大将棋 "dai shōgi") is a large-board variant of shogi (Japanese chess). 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 (which were at some points of time the most prestigious forms of shogi being played), 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 (summarised below with the listing of most known alternative moves) 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 (or princes). 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 (or 先手 "sente" and 後手 "gote"), play on a board ruled into a grid of 25 "ranks" (rows) and 25 "files" (columns), 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 (or roughly most to least powerful) 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 (commonly red instead of black); 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.
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.
Game play.
The players alternate making a move, with Black moving first. (The traditional terms 'black' and 'white' are used to differentiate the sides during discussion of the game, but are no longer literally descriptive.) A move consists of moving a single piece on the board and potentially "promoting" that piece or displacing ("capturing") 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 (meaning another piece controlled by the moving player).
Each piece on the game moves in a characteristic pattern. Pieces move either "orthogonally" (that is, forward, backward, left, or right, in the direction of one of the arms of a plus sign, +), or "diagonally" (in the direction of one of the arms of a multiplication sign, ×). 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. (The Buddhist spirit and furious fiend are similar, but they only appear as pieces promote.)
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. (If a friendly piece occupies an adjacent square, the moving piece may not move in that direction; if an opposing piece is there, it may be displaced and captured.)
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 (except the wood general), 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 (2, 3, or 5) of free (empty) squares along a straight line in certain directions. Other than the limited distance, they move like ranging pieces (see below).
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 (unless it first changes direction to avoid it), 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 "yyy"K 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 (combinations of) 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 (自在)天王 "(jizai) tennō"
Prince 太子 "taishi"
Hook mover 鉤行 "kōgyō"
Long-nosed goblin 天狗 "tengu"
Capricorn 摩𩹄 "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. (rlRB3fbR2)
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 𠵇犬 "kiken"
Donkey 驢馬 "roba"
Ram's-head soldier 羊兵 "yōhei"
Lance 香車 "kyōsha"
Pawn 歩兵 "fuhyō"
Promotion.
When a piece first makes a capture, it promotes. (If it can: a few important pieces do not promote.) 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" (the enemy camp), 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"
Check and mate.
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 (emperor or prince) 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. (This rule may be relaxed in casual games.)
Another possible, if rather uncommon, way for a game to end is repetition ("sennichite"). 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 (see above).
Promoted pieces have a + added in front of the letter. (e.g., +CC for a wizard stork (promoted Chinese cock). 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 (as seen from Black's point of view) and 25y being the bottom left corner. (This method of designating squares is based on Japanese convention, which, however, uses Japanese numerals instead of letters. For example, the square 2c is denoted by 2三 in Japanese.)
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 (using the interpretations of the English-language sources):
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(s). 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.