mahjong jpRiichi Mahjong is the Japanese variant of Mahjong that focuses on strategy, precise scoring, and unique rules like Riichi (a declaration of a ready hand). It requires players to fulfill at least one Yaku (scoring pattern) to declare aRiichi Mahjong is the Japanese variant of Mahjong that focuses on strategy, precise scoring, and unique rules like Riichi (a declaration of a ready hand). It requires players to fulfill at least one Yaku (scoring pattern) to declare a