Secondly, the broad set of hidden information of the tiles makes Mahjong a much more difficult imperfect-information game than previously studied ones, such as Texas hold'em poker. Thirdly, the playing rule of Mahjong is much more complicated because of the various actions involved.

The game and its regional variants are widely played throughout East and Southeast Asia and have also become popular in Western countries. The game has also been adapted into a widespread online entertainment. Similar to the Western card game rummy, mahjong is a game of skill, strategy, and luck.