Trishogi

Trishogi is a shogi variant for two players created by George R. Dekle Sr. in 1987. The gameboard comprises 9×10 interlocking triangular cells. The game is in all respects the same as shogi, except that piece moves have been transfigured for the triangular board-cell geometry.
Trishogi was included in "World Game Review" No. 10 edited by Michael Keller.
Game rules.
Trishogi has the same types and numbers of pieces as shogi, and all normal shogi rules apply, including initial setup (see diagram), drops, promotion, check, and checkmate. As in shogi, pieces capture the same as they move. But the triangular geometry creates special move patterns for the pieces.
Piece moves.
The diagrams show how the unpromoted pieces move. As in shogi, a "dragon king" (promoted rook) moves as a rook and as a king. A "dragon horse" (promoted bishop) moves as a bishop and king.
References.
Bibliography