Sho shogi

Sho shogi is a sixteenth century Japanese chess variant recognized as the immediate historical predecessor of modern shogi, played on the same nine by nine board with twenty one pieces per side and the same basic starting setup as contemporary shogi, apart from one distinguishing addition, an extra piece called the drunk elephant positioned directly in front of the king. Historical records indicate that the drunk elephant piece was eliminated from play during the reign of Emperor Go-Nara, who ruled from 1526 to 1557, and that the drop rule allowing captured pieces to be reintroduced to the board under their capturer's control was introduced around the same period, together producing the form of shogi recognized and played today. As in modern shogi, two players alternate moving pieces that travel orthogonally, diagonally, or in a knight-like jumping pattern depending on their type, aiming to capture the opponent's king, with some pieces gaining expanded movement options upon reaching the far ranks of the board and being promoted. In Sho shogi specifically, the drunk elephant piece promotes into a crown prince that functions as a second king, meaning a player must capture both royal pieces, not merely one, in order to secure victory.