Early versions of dai shogi can be traced back to the Kamakura period, from about AD 1230.
It was the historical basis for the later, much more popular variant chu shogi, which shrinks the board and removes the weakest pieces.
Fujiwara no Yorinaga, tutor to the crown prince, recorded playing dai shogi, in his diary, the Taiki, written between 1135 and 1155 AD.
[1] Other than the additional pieces (the iron and stone generals, knights, angry boars, cat swords, evil wolves, violent oxen, and flying dragons, which all promote to gold generals), the rules of dai shogi are thought to have corresponded very closely to those of its descendant chu shogi.
Unlike standard shogi, pieces may not be dropped back into play after capture.
Two players, Black and White (or 先手 sente and 後手 gote), play on a board ruled into a grid of 15 ranks (rows) and 15 files (columns) with a total of 225 squares.
[1] The squares are undifferentiated by marking or color, unlike a Western chess board.
The pieces are wedge-shaped and their orientation indicates which player they belong to, as they point toward the opposing side.
(Sometimes the queen is called the "free king", a direct translation of its Japanese name.
Pieces which only appear upon promotion, that is, names which only occur written in red, are marked with an asterisk.
The queen could also be abbreviated FK (for free king) and the kirin as Ky (for kylin).
The step movers are the king, drunk elephant, blind tiger, ferocious leopard, generals, angry boar, cat sword, evil wolf, go between and the 15 pawns on each side.
The violent ox and flying dragon can move along a limited number (2) of free (empty) squares along a straight line in certain directions.
Many pieces can move any number of empty squares along a straight orthogonal or diagonal line, limited only by the edge of the board.
This is reset by leaving the zone and reentering: promotion is possible on such a reentry even without a capture.
If a piece that cannot retreat or move aside advances across the board until it reaches the other side, it is trapped.
By default continuation legs can go into all directions, but can be restricted to a single line by a modifier 'v' ("vertical", interpreted relative to the piece's current position on its path).
The default modality of all legs is the ability to move and capture: other possibilities are specified explicitly.
(fbRK) Because it cannot move orthogonally, an unpromoted bishop can only reach half the squares on the board.
(B) Because it cannot move orthogonally, an unpromoted cat sword can only reach half the squares on the board.
A similar move without capturing leaves the board unchanged, which is a way to pass a turn.
Because of its unusual movement, an unpromoted kirin can only reach half the squares on the board.
This power includes igui and skipping a turn (see "Lion"), but not moving off the diagonal.
(BrlbRf[avW]fD) Because it cannot move orthogonally, an unpromoted bishop can only reach half the squares on the board.
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 who captures the opponent's sole remaining king or prince wins the game.
The very artificial situation of a smothered stalemate, where no moves are possible (even those that would expose the king), is not covered in the historical sources.
The Chess Variant Pages rule this as a loss for the stalemated player, for definiteness.
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 modifications have been made for dai shogi.