Microshogi

Microshogi is a Shogi variant played on a 4×5 board with hybrid pieces -- non-standard pairings of standard units:

• Bishop / Tokin
• Gold General / Rook
• Silver General / Lance
• Pawn / Knight
• King

A piece is promoted (flipped) whenever it captures another piece. This is mandatory even when the flip side is a weaker unit.

Also unlike 9×9 Shogi, captured pieces held in reserve can be dropped without restriction:

• A piece can be dropped with either side up.
• A piece can be dropped onto a rank that prohibits it from any further move.
• A pawn can be dropped onto the same column as another allied pawn.
• A pawn can be dropped to give immediate checkmate.

Microshogi is believed to have been designed by Shogi Grand Master Yasuharu Oyama (1923-1992).