Rule variations
Given the complexity to the rules of Japanese mahjong, the rules are even made more complicated by the existence of rule variations enforced among different groups and organizations.
Variation table
| Rule | WoRR | Ema2 | JpmlA | JpmlB | NPM | Skoui | SkouC | MuMa | RmuA | RmuB | RmuC | 101 | Tenho | Skyos | Korea | Uspml | Montr |
|---|
Rulesets
- WoRR
- Word Riichi Rules for the tourney in France, 2014. This ruleset is still in development. Not all details have been decided yet.
- Ema2
- European Mahjong Association (EMA) Riichi Competition Rules (RCR) from 2012
- JpmlA
- Japan Professional Mahjong League (JPML) ruleset A
- JpmlB
- Japan Professional Mahjong League (JPML) ruleset B
- NPM
- Nihon Pro Mahjong (NPM)
- Skoui
- Saikouisen, the oldest Japanese professional league
- SkouC
- Saikouisen Classic
- MuMa
- Mu Mahjong
- RmuA
- Real Mahjong Unit (RMU) ruleset A
- RmuB
- Real Mahjong Unit (RMU) ruleset B
- RmuC
- Real Mahjong Unit (RMU) ruleset C
- 101
- Ruleset of 101, another Japanese league
- Tenho
- Tenhou.net, a popluar internet game site
- Skyos
- Saikyousen, a tournament in Japan run by Takeshobo
- Korea
- Korean Mahjong League (KML)
- Uspml
- United States Professional Mahjong League (USPML)
- Montr
- Mahjong Montreal, Canada
Agari
Agari yame
Allow the dealer to end the hanchan prematurely if he wins the south 4th hand and ends up in first place, or if that hand becomes an exhaustive draw and the dealer ends up first.
- Ari – Allow the dealer to end the hanchan prematurely.
- Nashi – The game must continue until the seat winds rotate again.
Double ron
Score two winning declarations at the same time.
- Ari – Discarder of the winning tile must pay both hands separately. Riichi sticks are collected by the first winner to his right. Some rules entitle the other winner to one of these riichi sticks if he has declared riichi during this hand.
- Check – Like ari, but the fourth player must reveal a non-winning hand, so that he cannot intentionally avoid the triple ron abortive draw.
- Nashi – Atamahane, or head bump. Only the first win closest to the discarder is recognized.
Furiten riichi
Allow players to declare riichi while they are fuiten due to their own earlier discards.
Ryanhan shibari
Impose a two-han minimum at five or more honba (number of table counters). The two han must both come from yaku.
- Ari – Require two han from yaku at five or more honba.
- Nashi – One han from yaku is always enough.
Triple ron
Score three winning declarations at the same time.
- Ari – Discarder of the winning tile must pay all three hands separately. See double ron ari for distribution of riichi sticks.
- AtaH. – Atamahane, or head bump. Only the first win to the discarder's right is recognized.
- Abort – Do not score any hand, instead abort the hand with an abortive draw (tochuu ryuukyoku).
Atozuke
Allow the hand to win even if there exists no yaku that is satisfied with all wait tiles. Atozuke nashi, also called sakizuke ari, requires all winning possibilities to satisfy at least one same yaku. Sakizuke requires some
- Ari – Atozuke: Allow determination of yaku after determining the winning tile.
- Nashi – Sakizuke: Require a fixed yaku no matter how the hand wins.
Chombo
Points
Point variation on the penalty points may be applied.
- Standard - The penalized must pay the equivalent of a mangan tsumo, just only in reverse.
- Mod - Modified amounts to the point penalty may be specified.
Toppling tiles
A penalty may be applied to toppling tiles of off the dead wall.
- Ld6c – If at least one tile from the dead wall is toppled, then the hand is declared dead. If six or more are toppled, then chombo is applied.
- Comp – This is a computer game. The rules infraction cannot occur.
Wall toppling
A penalty may be applied to toppling tiles of off the live wall.
- 6c – If six or more are toppled, then chombo is applied..
- Comp – This is a computer game. The rules infraction cannot occur.
Dora
Furiten
If a non-riichi player ignores a winning tile, then temporary furiten is applied. Different rules apply as to when this status wears off.
- Turn – The player's next own discard ends temporary furiten. If the turn is skipped due to other players' pon calls, temporarily furiten is retained.
- Call – The players next own discard ends temporary furiten, but also any player's call of chii, pon, or kan, even for a concealed kantsu, ends temporary furiten.
Kuikae
This allows a player to call pon or chii on a tile, then afterwards discard the same tile, or a tile which would have completed the two revealed tiles at the other end of the sequence (switching chii).
- Full – Allow to discard any tile.
- Swap – Forbid discarding the same tile, allow switching chii.
- Nashi – Forbid discarding the same tile, forbid switching chii.
Kuitan
Allow the 1-han yaku tanyao (all simples) to be awarded to an open hand.
- Ari – Allowed
- Nashi – Not allowed
- Option – Tenhou.net offers both rules in different settings. One of the game rooms is set for both kuitan nashi snd akadora nashi. However, there is no setting for one or the other exclusively. The Korean rules write "concealed hand only selective", which sounds as if kuitan were an optional rule.
Naki
Variation may apply on tile calls. If several players call chii, pon, or ron on the same tile, this rule decides who will get the tile. Kan calls are treated like pon calls.
- Pon – Like pon above, but keep in mind that this is a computer game (C), not a ruleset for live play.
- Time – Pon trumps chii if called at the same time, otherwise the first call stands. Ron trumps anything, even if called slightly later.
Pao
Pao applies to an alternative point exchange, in the event of making foolish discards, which gives players particular advantages.
Daisangen and daisuushii
Impose a liability payment on the player who has dealt the third ponned dragon tile, or the fourth ponned wind tile, if the caller wins with daisangen (big three dragons) or daisuushii (big four winds) later.
- Ari – Liable player pays full on tsumo, half on ron.
- Nashi – No liability for daisangen or daisuushii.
Renchan
Renchan are additional hands, where the wind rotation is not applied. Instead, the wind positions remain the same for an extra hand.
- Agari – The hand is repeated only when East wins.
- Tenpai – The hand is repeated when East wins, or when East is tenpai upon exhaustive draw.
- Nanba – The hand is repeated when East wins, or when East is tenpai upon exhaustive draw, or when there is any exhaustive draw during the nanba (south round).
- Option – The rules allow two possible options, agari and tenpai.
Suukantsu
Impose a liability payment on the player who has dealt the fourth kanned tile, if the caller wins with suukantsu (four kantsu) later.
- Ari – Liable player pays full on tsumo, half on ron.
- Nashi – No liability for suukantsu.
Scoring
Scoring allows some flexibility to the rules regarding the start and end scores. Likewise, the oka and uma may be adjusted as well.
Tochuu ryuukoku
Abort a hand and repeat it at the next honba (number of table counters) in case of nine terminals and honors, same wind discards, four riichi declarations, or four kantsu declarations. Some rules abort the hand upon a triple ron; that is not covered by this rule, instead see triple ron.
- Ari – Abort and reshuffle in these situations.
- Nashi – Do not recognize any of these abortive criteria. Play every hand until a winning declaration or exhaustive draw. Do not allow a fifth kan declaration nonetheless.
Yaku
Different yaku may be subject to rule variation. Some are simply not considered standard.