Mahjong rules may vary in different regions of China. This is especially true for the scoring and bonus system, which is quite complex.
The rules of mahjong outside of China also differ from the classic version. So, in Japan, for example, a modification of the rules was developed for playing with three people. In Kora, its classic rules were also slightly modified. Mahjong, popular in the USA, also has its own nuances.
A sign of the era of new technologies is computer versions of mahjong. However, it is necessary to distinguish true mahjong from solitaire with the same name. The latter is a game for one player, similar to card solitaire, but this Mahjong solitaire is played with dice for the Chinese game.