Mahjong solitaire is a solitaire matching game that uses a set of Mahjong tiles rather than cards. It is also known as Shanghai solitaire, electronic or computerized mahjong, MahJong solitaire, solitaire Mahjong and, erroneously, as Mahjong. The tiles come from the four-player game popular in East Asia known as Mahjong. The 144 tiles are arranged in a special four-layer pattern with their faces upwards. A tile is said to be open or exposed if it can be moved either left or right without disturbing other tiles. The goal is to match open pairs of identical tiles and remove them from the board, exposing the tiles under them for play. The game is finished when all pairs of tiles have been removed from the board or when there are no exposed pairs remaining.
Mahjong solitaire can be played using genuine tiles and a special wooden frame for set-up. Usually though, it is played in an electronic form as a computer game. This removes the tedium of set-up and the temptation to cheat. Some electronic Mahjong solitaire games offer extra options, such as (1) changing the tile set and patterns from the traditional tiles to flowers, jewels or other items that may be easier to match up at a glance, (2) playing a series of different layouts with varying levels of difficulty (usually given Chinese names such as 'the ox' or 'the snake'), or (3) adding "wildcard tiles" and other tiles that have special functions. These games also have an optional time limit. They may also offer hints/cheat options such as the ability to have a match found for the player or to backtrack and undo already made moves. Additionally, most implementations of the game arrange the tiles in such a way that the game is solvable in at least one way.
Mahjong solitaire can be played either solo or with a partner, in which case the aim is to accumulate the most pairs, to be the last one to match a pair, or to score the most points. Points are gained for each pair removed, with bonus points for removing matched pairs in sequence or removing pairs in sequence that are parts of sets. Using traditional mahjong tiles, the sets include the dragons, the flowers, the seasons, and the winds (with the winds being worth the most bonus points).
Players should open up new tiles with every pair they eliminate. Choosing obvious pairs from the top levels will often end the game prematurely (i.e. lose) by leaving essential tiles under cover