Heian dai shogi (Japanese: 平安大将棋 'Heian (Era) large chess') is an early large board variant of shogi (Japanese chess) as it was played in the Heian period.
[1][2] Unfortunately, this description does not give enough information to actually play the game, but this has not stopped people from attempting to reconstruct this early form of 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 13 ranks (rows) by 13 files (columns) for a total of 169 squares.
The knight can jump, that is, it can pass over any intervening piece, whether friend or foe, with no effect on either.
Many pieces can move any number of empty squares along a straight orthogonal or diagonal line, limited only by the edge of the board.
The ranging pieces are the flying dragon, side mover, free chariot and lance.
The characters inscribed on the backs of the pieces to indicate promoted rank may be in red ink.
If an unpromoted knight reaches the farthest rank without capturing a piece, it can no longer promote.
If an unpromoted lance reaches the farthest rank without capturing a piece, it can no longer promote.
If an unpromoted pawn reaches the farthest rank without capturing a piece, it can no longer promote.
In practice this winning condition rarely happens, as a player will resign when checkmated, as otherwise when loss is inevitable.
There is one other possible (but fairly uncommon) ways for a game to end: repetition (千日手 sennichite).
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 heian dai shogi.
The first letter represents the piece moved: P = pawn, L = lance, N = knight, GB = go between, FC = free chariot, FT = fierce tiger, I = iron, C = copper, SM = side mover, S = silver, G = gold, FD = flying dragon, K = king.