Annan shogi

Annan shogi, also known as Korean shogi, is a variant of shogi, the Japanese strategy game often called Japanese chess. It is played on the standard nine-by-nine shogi board and is described as one of the more popular shogi variants within Japan's shogi-playing community. Its defining rule departs from ordinary shogi: when a piece has a friendly piece positioned directly behind it, it temporarily gains that supporting piece's movement ability in addition to, or instead of, its own normal moves. This support mechanic rewards players for keeping their pieces in a tight, mutually reinforcing formation, since a weak piece can effectively borrow the fighting power of whatever stronger piece is guarding it from behind, changing the tactics around piece placement and defense compared to standard shogi.