Dai dai shogi

Dai dai shogi, meaning huge chess, is a large-board variant of shogi, or Japanese chess, that dates back to the 15th century and is based on the earlier and somewhat smaller dai shogi. It is played on a 17 by 17 board, considerably larger than standard shogi, and its pieces have an extended range of movement compared to smaller shogi variants, along with a distinctive promotion by capture rule that makes it the smallest board variant of shogi known to use that mechanism. Historical documentation of its exact rules is sparse and at points contradictory, and surviving sets appear to have been made mainly for display, leaving real doubt about how widely, if ever, the game was actually played.