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 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.
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. 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 is compulsory on capture.

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 100 moves for these pieces. The pieces are of slightly different sizes. From largest to smallest 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.
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kōgyōGold general
Long-nosed goblin天狗tengu
Capricorn*摩?makatsuGold general
Peacock孔雀kujaku
Soaring eagle飛鷲hijū
Horned falcon角鷹kakuō
Queen奔王honnō
Rushing bird行鳥gyōchōFree demon
Free demon 奔鬼honki
Free dream-eater 奔獏honbaku
Water buffalo水牛suigyūFree dream-eater
Flying ox飛牛higyū
Soldier兵士heishi
Dragon king龍王ryūō
Dragon horse龍馬ryūme
Lion獅子shishiFurious fiend
*Furious fiend奮迅funjin
Racing chariot走車sōsha
Rook飛車hishaGold general
Bishop角行kakugyōGold general
White horse白駒hokku
Whale鯨鯢keigei
Standard bearer前旗zenki
Vermillion sparrow朱雀suzaku
Turtle-snake玄武genbu
Blue dragon青龍seiryū
White tiger白虎byakko
Right chariot右車usha
Left chariot左車sasha
Side dragon横龍ōryūGold general
Dove鳩槃kyūhan
She-devil夜叉yashaGold general
Golden bird金翅kinshi
Great dragon大龍dairyū
White elephant白象hakuzō
Lion dog狛犬komainuGreat elephant
*Great elephant大象taizō
Wrestler力士rikishiGold general
Guardian of the Gods金剛kongōGold general
Buddhist devil羅刹rasetsuGold general
Golden deer金鹿konroku
Silver hare銀兎ginto
Fierce eagle猛鷲mōjū
Old kite古鵄kotetsuLong-nosed goblin
Violent ox猛牛mōgyū
Flying dragon飛龍hiryūGold general
Old rat老鼠rōsoWizard stork
*Wizard stork*仙鶴senkaku
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mōyū
Side mover横行ōgyōGold general
Vertical mover竪行shugyōGold general
Reverse chariot反車hensha
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
Drunken elephant醉象suizōPrince
Neighboring king近王kinnōStandard bearer
Blind tiger盲虎mōko
Blind monkey盲猿mōenMountain witch
*Mountain witch山母sambo
Ferocious leopard猛豹mōhyō
Reclining dragon臥龍garyū
Chinese cock淮鶏waikeiWizard stork
Old monkey古猿koen
Evil wolf悪狼akurō
Angry boar嗔猪shincho
Cat sword猫刄myōjin
Coiled serpent蟠蛇banja
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ushō
Left general左将sashō
Gold general金将kinshō
Silver general銀将ginshō
Copper general銅将dōshō
Tile general瓦将gashō
Iron general鉄将tesshō
Wood general木将mokushō
Stone general石将sekishō
Earth general土将doshō
Go-between仲人chūnin
Knight桂馬keimaGold general
Howling dog*?犬kiken
Donkey驢馬robaGold general
Ram's-head soldier羊兵yōhei
Lance香車kyōsha
Pawn歩兵fuhyō

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 - Racing 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

The queen could also be abbreviated FK and the kirin as Ky.

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

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 soldier 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 on 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.

Promotion

The vast majority of pieces cannot promote. Those that can promote, however, must promote at the end of their first capturing move. Promotion is indicated by turning the piece over after it moves, revealing the character for the promoted piece. There are no promotion zones; dots on the board that usually represent promotion zones are present after the sixth rank only as a placement guide for initial setup. All this is as in dai dai shogi.
Promoting a piece has the effect of changing how that piece moves: see the table above for what each piece promotes to.
Pieces which are already promoted cannot promote again, except as follows:
Any piece promoted or not, that captures a Deva or teaching king promotes to a teaching king. This is brought about by replacing it on the board with the captured piece. Similarly, any piece that captures a dark spirit or Buddhist spirit promotes to a Buddhist spirit. This is sometimes expressed as the piece being contagious: when something captures a contagious piece type, it becomes that piece type. The only exception is royal pieces which promote to their normal promoted forms or stay as they are if unpromotable or already promoted.
It is not clear what happens if a multi-capturing piece such as a lion or a lion dog captures two different contagious piece types in one turn, e.g. a lion capturing both a teaching king and a Buddhist spirit on the same turn. Although the situation is very unlikely to arise, an official of the Japanese Chu Shogi Association has suggested in discussion with H. G. Muller that the multi-capturing piece would promote to the last piece captured. In the case of a lion dog capturing two pieces on the same orthogonal or diagonal, the official claimed that it would not be permitted to jump over the first piece, capture the second, and then move back to capture the first, though Muller admits that the logic did not "make much sense" to him and that he would be happy with the option to choose.
Otherwise, pieces don't promote more than once: they only have two sides.

Individual pieces

In the diagrams below, the different types of moves are coded by symbol and by color: Blue for step moves, yellow for jumps, green for multiple capture, and pink for range moves, as follows:
Piece names with a grey background are present at the start of the game; those with a blue background only appear with promotion. 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 endpoint, 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.
There are many divergent descriptions in the Edo-era sources. However, almost all the pieces in tai shogi already appear either in dai dai shogi or maka dai dai shogi, and so they are presented here identically to how they are on the Wikipedia articles for those two games. Refer to those pages for footnotes detailing divergent moves. Footnotes are presented as usual for pieces that do not appear in smaller games.

Repetition

A player may not make a move if the resulting position is one that has previously occurred in the game with the same player to move. This is called repetition. Note that certain pieces have the ability to pass in certain situations. Such a pass move leaves the position unchanged, but it does not violate the repetition rule, as it will now be the turn of the other player to move. Of course, two consecutive passes are not possible, as the first player will see the same position as before.
However, evidence from chu shogi problems suggests that this at least does not apply to a player who is in check or whose pieces are attacked, as otherwise one could win via perpetual check or perpetual pursuit. The modern chu shogi rule as applied by the Japanese Chu Shogi Association is as follows, and presumably tai shogi should be similar. If one side is making attacks on other pieces with his moves in the repeat cycle, and the other is not, the attacking side must deviate, while in case of checking the checker must deviate regardless of whether the checked side attacks other pieces. In the case of consecutive passes, the side passing first must deviate, making turn passing to avoid zugzwang pointless if the opponent is in a position where he can pass his turn too. Only the fourth repetition is forbidden by these rules. If none of these are applicable, repetition is a draw.

Check and mate

When a player makes a move such that the opponent's 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 emperor or prince is in check and no legal move by that player will get the emperor or prince out of check, the checking move is also a mate, and effectively wins the game. If a player has both an emperor and one or more princes in play, then the player need not move only one out of check.
Recall that an emperor can only capture a royal piece if that royal piece is unprotected. This prohibition applies even if the opponent's last royal piece is being captured: here "protected" means that the opponent could recapture if we ignore that he has just lost his last royal.

Game end

A player who captures the opponent's sole remaining emperor or prince wins the game. Thus a player who is checkmated or stalemated will lose. In practice this rarely happens; a player will resign when loss is inevitable and the king will be taken on the opponent's next move because of the tradition that it is seen as an embarrassment to lose. The very artificial situation of a smothered stalemate, where no moves are possible, is not covered in the historical sources. On their pages for chu shogi and dai shogi, The Chess Variant Pages rule this as a loss for the stalemated player, for definiteness.
A player who makes an illegal move loses immediately.
There is a rule that draws cannot be agreed.

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 as follows. Note that these use the move interpretations of The Shogi Association, e.g. the lion dog as only a three-square limited ranging piece in all directions, with no lion power. They also make the additional change that the prince is allowed to promote to emperor, although TSA rules do not allow this.
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
Racing 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 Chariot
Howling Dog
Lance
Old KiteLong-Nosed Goblin89
Poisonous SnakeHook Mover
Eastern BarbarianLion22
Dark SpiritBuddhist Spirit35
DevaTeaching King29
Flying HorseQueen21
Neighbouring KingStandard-Bearer15
Old RatWizard Stork15
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.