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 essentially a merger of two other large-board shogi variants: dai dai shogi and maka dai dai shogi. Almost all the pieces of those two smaller games are included, and where the same pieces are found, they move the same way. Additionally, many of the tai shogi pieces not from those two games already appear in the even more popular chu shogi. Only nine extra pieces are added that do not appear in any smaller games – the peacock, soldier, vermillion sparrow, turtle-snake, side dragon, golden deer, silver hare, fierce eagle, and ram's-head soldier. (Indeed, two of the Edo-era sources generally do not describe a piece for tai shogi if it exists in a smaller variant.)
The promotion rule is contested. Dai dai shogi and maka dai dai shogi have very different promotion rules. The promotion rules given on the Japanese Wikipedia are similar to those of maka dai dai shogi: almost all pieces promote, but most to the lowly gold general, even if they are much more powerful; and many weak pieces turn into "free" versions of themselves (in which stepping moves are replaced by unlimited ranging moves in the same directions). However, the promotion rules given in English-language sources are similar to those of dai dai shogi: most pieces do not promote. Both agree that promotion is compulsory upon capture if the piece can promote.
In maka dai dai shogi with its demotions, The Chess Variant Pages suggest that promotion is only compulsory when capturing a promoted piece, which seems more reasonable because otherwise the most powerful pieces would quickly disappear. However, in tai shogi non-promoting copies of those powerful pieces can be obtained by promoting some weak pieces.
The difference is unusual: in all smaller variants, Japanese Wikipedia agrees with the English-language sources on promotions, even though it does not always agree on the moves. There are additionally some confusions in the Japanese Wikipedia promotions: for example, the fragrant elephant is said to exist in tai shogi, but without a piece promoting into it. Because of this, the promotions from the English-language sources have been followed throughout this article, with alternatives given in the footnotes. That is, most pieces do not promote, and promotion (if possible) is compulsory on capture.
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 100 moves for these pieces. The pieces are of slightly different sizes. From largest to smallest (or roughly most to least powerful) they are:
1 Emperor 1 Prince 1 Hook mover 2 Long-nosed goblins 1 Capricorn 2 Peacocks 2 Soaring eagles 2 Horned falcons 2 Queens 1 Rushing bird 2 Free demons 2 Free dream-eaters 2 Water buffalos 2 Flying oxen 2 Soldiers 2 Dragon kings 2 Dragon horses 1 Lion 2 Racing chariots 2 Rooks 2 Bishops 2 White horses 2 Whales 2 Standard bearers 1 Vermillion sparrow 1 Turtle-snake 1 Blue dragon 1 White tiger 1 Right chariot 1 Left chariot 2 Side dragons 2 Doves 1 She-devil 1 Golden bird 1 Great dragon 2 White elephants 1 Lion dog 1 Wrestler 1 Guardian of the Gods 1 Buddhist devil 2 Golden deer 2 Silver hares 2 Fierce eagles 1 Old kite 2 Violent oxen 2 Flying dragons 2 Old rats 2 Enchanted badgers 2 Flying horses 2 Prancing stags 2 Violent bears 2 Side movers 2 Vertical movers 2 Reverse chariots 1 Phoenix 1 Kirin 2 Poison snakes 1 Northern barbarian 1 Southern barbarian 1 Eastern barbarian 1 Western barbarian 2 Blind bears 1 Drunken elephant 1 Neighbor king 2 Blind tigers 2 Blind monkeys 2 Ferocious leopards 2 Reclining dragons 2 Chinese cocks 2 Old monkeys 2 Evil Wolves 2 Angry boars 2 Cat swords 2 Coiled serpents 1 Deva 1 Dark spirit 1 Right general 1 Left general 2 Gold generals 2 Silver generals 2 Copper generals 2 Tile generals 2 Iron generals 2 Wood generals 2 Stone generals 2 Earth generals 2 Go betweens 2 Knights 2 Howling dogs 2 Donkeys 2 Ram's-head soldiers 2 Lances 25 Pawns
Several of the English names were chosen to correspond to rough equivalents in Western chess, rather than as translations of the Japanese names. (Sometimes the queen is called the "free king", a direct translation of its Japanese name. The kirin's name is sometimes anglicised as kylin.)
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.