Shatranj's army (King, Ferz, Elephant, Knight, Rook, Pawn) fights on an extremely narrow 4×16 board. The Elephant's two-square diagonal leap becomes a key maneuvering piece, since it's the only way to cross between the board's two edge files.
A historical variant documented by Hans Bodlaender in 1998. The army is identical to Shatranj's (King, Ferz, Elephant, 2 Knights, 2 Rooks, 8 Pawns), but the board is stretched into an extreme 4×16 rectangle. Seven different opening arrays are recorded historically; this implementation uses one of them. Pawns never get a double-step.
Simplification: the "bare king" rule is omitted — capturing the king directly ends the game. A stalemated side is simply treated as having lost (no legal moves = loss).