Riichi Mahjong Primer
This article will attempt to describe how to play riichi mahjong (Japanese Mahjong) online in a simple and concise way. Therefore, any instructions related to setting up the game are omitted for this guide.
Game Overview
Riichi mahjong is a 4-player tile-based board game with a heavy focus on luck. The goal of the game is to collect the most points.
You gain points by assembling winning hands. Winning hands that meet specific criteria score more points.
Each game is sorted into multiple rounds. For every round, only one player can win. A round ends when a player wins, when the tiles run out, or in certain specific conditions.
Turns
At the start of each round, each player is dealt 13 tiles. The East player always starts the first turn, followed by South, West, and North (in that order).
During your turn:
- Draw 1 tile.
- If this tile can complete a winning hand, you may declare a win by self-draw ("Tsumo").
- You may declare a quad ("kan") if conditions allow and if you want.
- You may declare "riichi" if conditions allow and if you want.
- Discard 1 tile.
After you discard, your turn is over. Other players may call the discarded tile if they can and want to. If the discarded tile is not called, the next player starts their turn.
After a player wins, the round ends. After 70 draws, the round also ends, even if there is no winner. When the round ends, tiles are reshuffled, and the next round starts.
Tiles
There are 36 types of tiles, and 4 of each type, for a total of 136 tiles. They can be grouped into two major categories:
Number Tiles. Each "suit" of numbered tile has tiles from 1-9. They can be used to form sequences, triplets, and pairs.
- Manzu (Characters) -
- These tiles are labelled in the Chinese characters (equivalent to the Japanese kanji) for 1-9. In online play, you'll often have the option to add 1-9 labels in the corner of the tile.
- Pinzu (Dots, Circles) -
- The number of circles is the number of the tile.
- Souzu (Bamboo, Bams, Sticks) -
- The 1-sou is a bird. The other tiles are green lines, the number of lines is the number of the tile.
Honor Tiles. Each honor tiles has a different character on it. They can be used to form triplets and pairs, but not sequences.
- Dragons -
- With dragon tiles, it is not important to know the meaning of the characters are. Thus, they can be referred to as "White", "Green", and "Red" respectively.
- Winds -
- These tiles are labelled in the Chinese characters for the 4 cardinal directions. In order, they are East, South, West, North. Knowing the direction of the wind tiles *is* important. Like the character tiles, the winds can be labelled N S W E in the top right corner if the website allows.
Winning Hands
A winning hand needs to meet two conditions:
- A winning shape. With two exceptions, winning hands are comprised of 4 "sets" + 1 "pair".
- A "yaku". Yaku are conditions or criteria that increase your hand's point value. In essence, a hand cannot win with 0 points, therefore a hand cannot win without any yaku. A yaku may rely on the tiles in the hand, or it may be based on how you win the hand.
- (Note: a hand may gain value via "dora" tiles, but if the hand has no value other than dora, it cannot win.)
Both these conditions will be described below.
Winning Shape
First, let's explain what "sets" and "pairs" are.
Sets
Sets, also called "melds", "groups", or "mentsu", are groups of 3-4 tiles of a specific type.
1. Sequences - sequences are three number tiles in sequential order, and of the same suit.
| Closed | Open |
|---|---|
   |
  
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Sequences may not "wrap around" from 9 to 1, so sequences of 891 or 912 are not allowed. Honor tiles cannot be used in sequences.
2. Triplets - triplets are three copies of the same tile. Any tile can be used in a triplet.
| Closed | Open |
|---|---|
 |
 
|
 |
 
|
Pairs
Pairs are two copies of the same tile, similar to a triplet.
| Pair |
|---|
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Winning Shape
As mentioned above, with a few exceptions, a winning shape is comprised of 4 sets + 1 pair, for a total of 14 tiles.
Example hand:
4 sets:
- 2 sequences ( ) + )
- 2 triplets ( ) + )
1 pair: ( )
However, you can only hold up to 13 tiles at a time. Therefore, you need to get hand that's 1 tile away from winning ("tenpai"), then either win by drawing a needed tile, or claiming it from another player's discard.
Ready Hand (Tenpai)
A ready hand, or a hand in "tenpai", is a hand that is one tile away from winning. Identifying ready hands is important, since a ready hand is required to win.
Ready hand #1 - 3 complete sets + 1 incomplete set + 1 pair:
3 sets:
- 1 sequence ( ))
- 2 triplets ( ) + )
1 pair: ( )
1 incomplete set ( )
This hand waits to complete the incomplete set of 56-pin. It may win off of:
- , forming a complete sequence, or
- , forming a complete sequence.
Ready hand #2 - 4 complete sets + 1 tile waiting to be paired:
4 sets:
- 2 sequences ( ) + )
- 2 triplets ( ) + )
1 tile waiting to be paired: ( )
It may win off , to complete a pair.
Ready hands may be interpreted in different ways, allowing the hand to win off multiple different types of tiles. For example:
This hand may win off either 
or , to complete a pair.
The section of the hand may be viewed as either ( sequence + tile waiting to be paired) or ( sequence + tile waiting to be paired). Therefore, it can win off either the 4 or the 7.
To Win
If you have a ready hand, and at least one yaku, you are eligible to win. You can win when another player discards a tile that completes the hand, or you draw the tile that completes the hand.
When another player discards a tile you can win with, call "ron". You may not declare ron if you are in furiten (see below for details).
When you draw the tile you can win with, call "tsumo".
Yaku
Yaku are specific criteria that gain you points. For example, All Triplets requires all 4 sets to be triplets. To repeat, a hand cannot win with 0 points, therefore a hand must have at least 1 yaku.
A hand can technically gain points with dora tiles. But if a hand has only dora tiles, and no yaku, it still can't win.
The simplest yaku is riichi. So long as you have not called an opponent's discarded tile (you haven't pressed "chii", "pon", and haven't pressed "kan" when it's not your turn), you may declare riichi when you have a ready hand.
More yaku will be covered later in the guide.
Furiten
When you are in furiten, you cannot win off other players' discards. You can still win by self-draw, however.
Discard Furiten
The most common way to enter furiten is when you previously discarded a tile that you can now complete a winning shape with. For example:
Waiting for: 
, , or
Say you discarded the in the past. You cannot win off any tile because you could've won with the 2-pin. If an opponent discards , you cannot win. You did not discard the , but you discarded a tile you could've won with - therefore, you cannot win with any tile.
It does not matter if the discarded tile wouldn't give any yaku. If you could've completed a winning shape with the tile, you are in furiten.
While furiten may be an annoying mechanic, it helps players defend against others. Because of the furiten rule, any tile another player discarded is 100% safe against that specific player.
To get yourself out of discard furiten, you may change your hand's shape so that it is no longer able to win with any of your previously discarded tiles.
Players will often get into furiten if they do not know the yaku, or have a non-guaranteed yaku. Therefore, knowledge of the yaku is important.
Other Furiten
There are two other types of furiten:
- If you decline to take the first possible win after declaring riichi, you enter permanent furiten.
- If you decline to take a win with a non-riichi hand, you enter furiten until your next draw. (This applies even if winning with that tile couldn't give you a yaku.)
This means that, after an opponent declares riichi, any tile anyone discards thereafter is safe against the riichi-declaring player.
Similarly, the tile the player to your left discarded is 100% safe against all 3 players for that turn only.
Tile Calls
Tile calls allow you to add discard tiles
Open Calls
Chii and pon are open calls. They let you claim tiles that opponents discard, allowing you to complete the hand faster, but prevent you from gaining certain yaku (most importantly, riichi), and make other yaku cheaper.
Chii - The call to complete a sequence. First, you need 2 tiles that can complete a sequence. Then, the player right before you (the player to your left) must discard a tile that completes the sequence. You may only call chii to the player to your left. This reveals the 2 tiles used for the call, and after revealing, the completed set is placed on the side of the table.
Pon - The call to complete a triplet. You must have 2+ tiles of the same type, then any opponent needs to discard another tile of that type. You may call pon from any player's discard. This reveals the 2 tiles used for the call, and after revealing, the completed set is placed on the side of the table.
After calling chii or pon, you discard a tile immediately, and it becomes the next player's turn. Therefore, when calling pon, you may skip other players' turns.
Calling comes with multiple downsides:
- After calling, you may not adjust the called set afterwards. So if you chii a 123 sequence, you may not change the sequence after drawing a 4.
- Calling reveals the set you completed. Other players may know the type and/or value of the hand once you call.
- Calling cheapens the hand, by preventing certain yaku, and reducing the value of other yaku. Therefore, when calling, you should have at least one yaku planned.
Also, under most rules, you cannot "swap call" - you cannot discard a tile that would complete the set you just called. For example, if you had call 4-sou with a 23-sou semi-sequence, you cannot discard a 1. If you pon a 5-man, you cannot discard another 5-man.
Kan
Kan is the call to complete a quad. It is complicated - new players don't need to worry about it. For the studious, there are three types of kan.
- Open kan - You have 3 tiles of the same type, then any opponent needs to discard another tile of that type. Works like pon does, including opening the hand.
- Closed kan - You have 3 tiles of the same type, then draw the 4th one. This call does not open the hand, so you may declare riichi after closed kan.
- Added kan - You previously called pon and draw the 4th tile of the same type.
Despite having 4 tiles, a kan is treated as a single set. Whenever you call kan, you draw a new tile, and your hand size increases by 1. Therefore, after 1 kan call, a ready hand will be 14 tiles, and a winning hand will be 15 tiles.
After calling kan, like chii and pon, you may not adjust the tiles used for the kan afterwards.
Calling kan will also reveal a new dora indicator. This may increase the value of anyone's hand, not just your own.
Wind Rotations
At the start of the game, players are assigned East/South/West/North randomly.
When the East player wins, the player's seat winds remain the same for the next round. When nobody wins and the East player has a ready hand, the seats also remains the same.
When a non-East player wins, the winds rotate in reverse player order. The East player becomes North. South becomes East. West becomes South. North becomes West.
Game Wind
The game itself has a wind, too. The game starts in the East wind.
After each player has been the East seat once, the game's wind changes. Like player order, the game's wind goes from East -> South -> West -> North.
Because the player seats do not change when the East player wins, whenever the East player does win, the game is extended by one round.
Game End
A "hanchan" (half game; South game) is the most common game length in riichi mahjong. In a hanchan the game lasts for 2 winds - East and South. After the South wind ends (8 game rounds minimum), the game ends.
However:
- If a player falls below 0 points, the game usually ends right then and there.
- If no player has reached the "target score" (usually 30,000 points), then the game continues to the West round. After the West round, the game may end (depending on the website) even if the target score is not yet.
Other Game Mechanics
Dealers
The dealer is always the player in the East seat. In online clients, the game is set up automatically, so the dealer does not set up the game. However, being dealer grants various bonuses:
- Dealers gain roughly x1.5 points for every hand they get.
- As mentioned: when a dealer wins, or when the round ends and the dealer has a ready hand, the seat winds do not change. This means that, whenever a dealer wins, the game is extended by 1 round. A dealer can theoretically win forever until a player is bankrupt.
However, when another opponent wins by self-draw ("tsumo"), the dealer pays twice as much as the non-dealers. Dealers do not pay extra when discarding another player's winning tile.
Round End
If no one wins, the round ends once 70 tiles have been drawn and discarded.
When a round ends this way, each player with a ready hand receives points from players without a ready hand.
- 4 players with a ready hand, or 0 players with a ready hand: No payments are made.
- 3 players with a ready hand: The non-ready player pays 1000 points to each player.
- 2 players with a ready hand: The non-ready players pay 1500 points, the ready players receive 1500 points.
- 1 player with a ready hand: The non-ready players each pay 1000 points to the ready player.
The round may also end in an abortive draw - abortive draws happen in rare conditions, so new players don't need to worry about them. If the round ends in an abortive draw For more details, see abortive draw.
Honba
Whenever East (the dealer) wins a round, when the game ends in an exhaustive draw, or when the game ends in abortive draw, the honba count increases by one. After a non-East player wins, honba are reset.
For each honba, the score of winning hands are increased by 300 points:
- If won by self-draw (Tsumo), each player pays 100 points to the winner.
- If won by another player's discard (ron), the discarding player pays 300 points to the winner.
Dead Wall
During each round, 14 tiles are unable to be drawn (the round ends before they can be drawn). These 14 tiles are known as the dead wall. Because the dead wall exists, sometimes you will be unable to get a needed tile.
Dora
At the start of each round, a dora indicator is revealed. The tile after the revealed dora indicator is the dora tile. For every dora tile in your hand, you gain 1 han.
For example, if is the dora indicator, is the dora. Having in your hand will increase your hand's value.
- Number tiles: , where indicator means is the dora.
- Dragons: -> -> ->
- Winds: -> -> -> -> (the same as the player order)
For each kan a player makes, a new dora indicator is revealed.
Uradora
If you declare riichi and win, the uradora are revealed. 1 uradora indicator is revealed for each regular dora indicator. Uradora indicators work like dora indicators (the tile after the indicator is the dora tile).
There is no way to know uradora before winning, so yradora are essentially random bonuses for winning with riichi. In general, ~30% of winning riichi hands contain at least 1 uradora.