Riichi Mahjong Scoring App

[Valda Atkeson]

JapaneseMahjong scoring rules are used for Japanese Mahjong, a game for four players common in Japan. The rules were organized in the Taishō to Shōwa period as the game became popular. [citation needed]

The scoring system uses structural criteria as well as bonuses. Player start scores may be set to any value. Usually, it is set to 20,000 to 30,000 points. Scores are counted using sticks of 10,000 points, 5,000 points, 1,000 points and 100 points. A game often ends when all the points of a player are lost, which is a situation called hakoten,[nb 1] dobon,[nb 2] buttobi,[nb 3] etc. However, some settings allow the game to continue, even if a player's score dropped below zero.

In the case of a draw, points are transferred according to the nō-ten bappu rule. In the event of a penalty, such as claiming a win with an illegal hand, then points are transferred via the chombo rule.

The actual points given are rounded up to the nearest 100. Even if the values of han and fu are the same, the points received for self-draw wins often slightly deviate from those received for discard wins because of rounding.

The method of calculating a winning hand's score in mahjong is quite tedious. Instead, hand values are fixed into a scoring table. Expert and professional players have this table memorized and can thus tell the value of a hand at a glance. Each of the table's point values is derived from the scoring equation and procedure with each corresponding han and fu values.

To use the table, simply look up the values that correspond to the han and fu counts of the hand. The top numbers in each cell indicate the payout from a player who discards a winning tile. The numbers in brackets indicate the payout for each player in the event the winning tile is self-drawn. If the winner is the dealer, each player pays the same amount. If the winner is a non-dealer, then the other two non-dealers pay the smaller number, while the dealer pays the larger number.

On plenty of occasions, a hand ends with all tiles drawn and the 14 tiles in the dead wall remain. Yet, no player wins the hand. This is the exhaustive draw. In this case, points may be exchanged barring any tenpai hands vs nōten hands. After each exhaustive draw, the counter increases by one.

In most rules when a dealer's hand is nōten, the dealer changes and the game wind may change. But if it's the last hand of the last round, in some rules, a game does not end if the dealer declares nōten.[2]

The dealer keeps count of the number of continuous dealer wins and draws by placing point sticks on the table. While point sticks are usually used for scoring, here they are used merely as counters, a visual aid. The initial count is zero. The number of counters increases by one when:

In the case of (1) or (3), the dealer remains the same. In the case of (2), when the dealer cannot declare tenpai, the dealer changes, but the number of counters increases regardless of whether the dealer declares tenpai. In all other cases, namely when only a non-dealer wins, the count is reset to zero.

Other settings for chombo apply point penalties after the game's conclusion. This is especially the case under tournament settings. Under this method, players do not benefit with any point gains. Instead, the infracted player solely takes a point deduction. The deduction may be set to any specified number.

At the end of the game, the final scores may be calculated. Under casual game settings, this calculation is not necessary. However, under more formal settings, it may be required. This calculation takes the game's scores and adjusts them according the setting of oka and uma, which were predetermined before the game. The calculation for each player is as follows:

In the optional rule wareme (割れ目, ワレメ; fissure, split), the player in front of whom the wall was split to indicate the end of the dead wall, acquires and pays double the normal points. They are doubled after the points for counters are added.[6] It is often especially called oya-ware (親割れ; parent's wareme) when the player is the dealer.

Japanese mahjong features a complex scoring system. Nearly every mahjong hand has a value in terms of han and fu, which determine its point value. The han and fu are then plugged into an equation to determine the score. Alternatively, a scoring table can be used to find the point value directly.

Players are encouraged to know yaku, their han values, and how much points a given hand is worth. This knowledge may help with various game decisions, particularly when calling riichi or abandoning the hand.

As a general rule, for every +1 han, the hand roughly doubles in value until reaching 4 han. There is a "cap" at 2000 base points (5 han; 4 han 40+ fu) - a hand that scores this much is called a mangan hand. Once reaching mangan, fu no longer matters for points, and han is reduced in value.

Every hand begins with a default of 20 fu. Any extra sources of fu are added, and then rounded up to the next multiple of 10. The exception is with chiitoitsu yaku, which is fixed to 25 fu (and not rounded).

The highest-scoring combinations are the yakuman patterns. A hand completing a yakuman is not scored for han and fu, but depending on the rules, it may be possible to combine multiple yakuman for an even larger hand.

The numbers for a ron payment are obtained by having the ronned player pay every other players points. Because rounding is done after this reassignment of points, it is sometimes the case that a win by tsumo is worth a few hundred more points than a win by ron.

Since the han and fu equation is always the same, it is possible to use a scoring table to score the hand. Simply calculate the hand's han and fu, then find the values on the table. See scoring table for the actual table.

Riichi mahjong is a Japanese variant of the ancient Chinese game of mahjong. It is a tabletop game that is played by four players, with each player having a hand which they must try and complete to win points from the other players. It shares similarities with Rummikub, and card games such as gin rummy and poker.

Riichi mahjong does not use the flower or season tiles found in Chinese sets, nor the joker tiles used in American Mah Jongg. As an optional rule, riichi mahjong can also be played with one five from each suit being replaced with a red five tile.

After a set has been called, the tiles are placed face-up to the right of the player who called them. The called tile is rotated so that it is sideways, and is positioned to indicate which player discarded it, e.g. if the right tile is turned sideways then it indicates the player to the right discarded it. For example, the sequence meld below indicates that the player to the left discarded the 6 sou tile in a 567 set.

A winning hand consists of 14 tiles (excluding kans), which will almost always be four sets plus one pair. A crucial condition for the player is that the winning hand must contain a yaku. A yaku is something special about the hand which increases its value. This is a key difference to Chinese mahjong and serves to stop players from winning quickly with extremely cheap hands, meaning that higher scoring hands are more plausible, increasing the strategy and excitement in the game. For beginners, the easiest to remember and aim for are:

A player who has called riichi can only call ron on their first opportunity. They cannot wait for their winning tiles to be discarded by specific players if they have already been discarded by somebody else (see furiten below).

While the disadvantages of riichi can seem worse than the advantages, the additional yaku and reverse dora are generally far more valuable, and it is usually more beneficial for the player to call riichi than to not, unless they have a hand which would be worth a lot regardless, or another player may have a high-value hand which would be bad to deal into.

The final main difference between riichi mahjong and other variants is the presence of dora. The dora is indicated by a face-up tile in the dead wall, which will mark the next tile in the suit as the dora. For example, if the face up tile is 3 sou, then 4 sou is the dora tile. A 9 tile indicates the 1 tile of the same suit, so 9 pin would indicate 1 pin as the dora. Winds and Dragons cycle as follows:

Some variants of mahjong have red fives in play. One 5 sou, one 5 man and one 5 pin will be coloured entirely red, and these red fives are one dora. Again, they do not count as yaku, and only make a difference after the hand has won.

If a player wins after declaring riichi, then the tiles in the wall under any displayed dora indicators also become indicators themselves (called ura-dora), doubling the number of possible dora for the winning player. This is one of the main advantages of declaring riichi.

It is also worth noting that tiles which have been discarded and called by another player still count towards furiten discards. For this reason called tiles are typically rotated and placed to indicate the seating of the player that discarded them (left tile is rotated for player to the left, right tile to the right, middle tile for opposing player).

Scoring is a complicated aspect of the game, and unless playing with physical tiles, the computer will do it for you. Guides already exist on how to score in detail. As a rule of thumb, the following chart is good enough for beginners to estimate what a winning hand will be worth:

A fairly common but optional rule is that if no players are over 30,000 points by the end of South, then the game will continue into West round, and keeps going until any player gets above 30,000 points.

It is worth noting that the conditions for ending the game will depend on the exact rules being played to. For example EMA Tournament rules will allow players to continue with negative points, and the game ends at the end of South round regardless of the score situation.

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