In Mahjong Police, players control a rookie detective who solves a variety of cases throughout Japan. In order to gather information about the culprit, they must challenge witnesses in games of four-player mahjong, where they must fulfill special criteria (such as not finishing last and winning with certain hands). If they correctly deduce the criminal, they must defeat them in a game of mahjong to arrest them.

In Mahjong Police, players control a rookie detective who solves a variety of cases throughout Japan. In order to gather information about the culprit, they must challenge witnesses in games of four-player mahjong, where they must fulfill special criteria (such as not finishing last and winning with certain hands). If they correctly deduce the criminal, they must defeat them in a game of mahjong to arrest them.