Heian dai shogi

Heian dai shogi is an early large-board variant of shogi, the Japanese chess family, played on a thirteen-by-thirteen board with thirty-four pieces of thirteen different types per side. It is documented in the Nichureki, an encyclopedic compilation dating to the Kamakura era, though the text describes gameplay associated with the earlier Heian period of the twelfth century, making it one of the oldest recorded large-board shogi variants. Two players compete, with Black moving first, maneuvering an expanded army across the wider board in a slower, more elaborate contest than standard modern shogi, which is played on a nine-by-nine board and permits captured pieces to be dropped back into play. Heian dai shogi predates the later, still larger dai shogi variant played on a fifteen-by-fifteen board, and its piece set and board size mark an intermediate stage in the historical growth of shogi variants before the game eventually settled on the smaller modern board.