Rules overview
The rules of Japanese mahjong are not completely fixed. The core mechanics are the same everywhere, so any comprehensive rules description is suitable for learning the game. Specific rulesets may then differ in finer details.
Rules summary
Japanese mahjong is quite complex with its many rules and special cases. This section provides an overview of the game, but a beginner will not be ready to play after reading just this. They should follow up with a tutorial linked below under Learning to play.
Game setup
Mahjong is played by four players with a set of 136 tiles. These tiles work similar to playing cards: There are three suits with numbered tiles from 1 to 9, and some suitless honor tiles. There are four copies of each individual tile in the set.
        
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36 tiles in the man suit |
        
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36 tiles in the pin suit |
        
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36 tiles in the sou suit |
      
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28 honor tiles |
These tiles are shuffled on the table, then the players build walls of face-down tiles. These walls serve as a stockpile to draw tiles from. Every player receives a hand of 13 tiles.
Objective
On each turn, the player picks a new tile from the wall, then discards an unnecessary one. It is sometimes possible to call and pick up an opponent's discard instead of drawing from the wall.
The first player to obtain a winning combination of 14 tiles scores points from his opponents: If the winning tile was drawn from the wall, the opponents share the payment. If the winning tile was a discard, the discarder must pay the entire hand value himself.
After a win, all tiles are reshuffled, and the next hand may begin. The player with the most points after a number of hands wins the session.
Hands and yaku
Winning hands of 14 tiles contain four melds of 3 tiles each, plus a pair. The pair consists of any two identical tiles. A three-tile meld may either be a consecutive sequence of same-suited tiles, or just any three identical tiles.
In the cases of kokushi musou and Chii toitsu, however, the regular composition of the hand is ignored.
In addition, a winning hand must have at least one yaku. A yaku is a special condition under which the win occurs, or a distinguished pattern within the hand's tiles.
Strategy
There are many ways to build a winning hand, some being more difficult and higher-scoring than others. Choosing which type of hand to go for, therefore what to discard each turn. takes judgment. Calling tiles from opponents may speed up the hand, but may make it worth less.
Discarding an opponent's winning tile is costly, because the entire value of the hand must be payed by the discarder. To defend against this, players can try to discard only safe tiles, thus destroying their own hands. Other times, players may decide to ignore their opponents and keep on building their own hands.
Learning to play
- Youtube playlist by HanaYoriUta, a very well presented tutorial and rules reference with over 3 hours runtime
- Mahjong for Dummies, an entire website for learning the game
After learning the rules, you can play online or join an offline group.
Specific rulesets
The core rules allows for some variation in the finer details. Before playing, one has to be familiar with the specific ruleset used.
- |Rules used on Tenhou.net
- EMA Riichi Competition Rules are commonly used at tournaments in Europe.
- USPML rules are common in the United States.