Three-man chess

Three-man chess is a chess variant for three players invented by George R. Dekle Sr. in 1984. The game is played on a hexagonal board comprising 96 quadrilateral cells. Each player controls a standard army of chess pieces.
Three-man chess was included in "World Game Review" No. 10 edited by Michael Keller.
Game rules.
The illustration shows the starting setup; each player's queen is placed to the left of his king. White moves first and play proceeds clockwise around the board. Pieces move the same as they do in chess, with some special features described below. Standard conventions apply including castling, a pawn's initial two-step option, "en passant", and promotion. The first player to checkmate an opponent wins the game.
Stalemate.
A player who is stalemated loses his turns to move, unless/until an opponent plays a move that releases the stalemate condition. While stalemated, his king is still subject to checkmate, and his other pieces are still subject to capture.
References.
Bibliography