Sannin Shogi
Sannin shōgi (三人将棋 three-person chess), or in full kokusai sannin shōgi (国際三人将棋 international three-person chess), is a three-person shogi variant invented circa 1930 by Tanigasaki Jisuke and recently revived. It is played on a hexagonal grid of border length 7 with 127 cells. Standard shogi pieces may be used, and the rules for capture, promotion, drops, etc. are mostly similar to standard shogi. (See that article for an explanation of these terms.) While piece movement differs somewhat from standard shogi, especially in the case of the powerful promoted king, the main difference in play is due to the rules for voluntary and mandatory alliance between two of the three players.
Read more about Sannin Shogi: Board and Setup, Movement On A Hexagonal Board, The Pieces and Their Moves, Capture, Drops, Castling, Promotion, Checkmate and Winning The Game, Other Rules, Alliances, Sample Game, See Also