Shogi

Shogi (将棋, shōgi; English: /ˈʃoʊɡi/, Japanese: [ɕoːɡi]), also known as Japanese chess, is an abstract strategy board game for two players. It is one of the most popular board games in Japan and is in the same family of games as Western chess, chaturanga, xiangqi, Indian chess, Makruk, and janggi. Shōgi means general's (shō 将) board game (gi 棋). The term shōgi is most commonly used to describe hon-shōgi ("standard shogi"), a term used to distinguish the most popular form of the game (with an 81-square board and 40 pieces) from other forms like ko-shogi (ancient shogi variants like chu shogi), modern shogi variants, and related games.

A distinctive feature of Shogi is that after a player has captured an opponent's piece, they retain these as "pieces in hand" (mochigoma), which can be dropped back into the game in a future turn. Shogi was the earliest historical chess-like game with this game mechanic. This drop rule is speculated to have been invented in the 15th century and possibly connected to the practice of 15th-century mercenary samurai switching loyalties when captured in battle. Due to the larger board and the drop rule, modern shogi has a significantly higher game tree complexity than FIDE chess, estimated at approximately 10²²⁶ compared to 10¹²³ for chess. Another key feature of Shogi is its decisiveness, as draws as very rare, occurring at a rate of 2-3% in professional games compared to a FIDE chess rate of over 50%. Furthermore, the first turn advantage in shogi is smaller than in chess, even when games are played by the strongest shogi engines.

The earliest predecessor of the game, chaturanga, originated in India in the 6th century, and the game was likely transmitted to Japan via China or Korea sometime after the Nara period. Shogi in its present form was played as early as the 15th century, while a direct ancestor without the drop rule was recorded from 1210 in a historical document Nichūreki, which is an edited copy of Shōchūreki and Kaichūreki from the late Heian period (c. 1120).