MahJong Rules

This document describes MahJong rules and their incarnation on the Internet MahJong Server (IMS).

• MahJong Tiles
• Sets of Tiles
• Games and Rounds
• A MahJong Game
• IMS Table Options
• IMS Scoring System

MahJong Tiles

The Character Suit

The Ball Suit

The Bamboo (or Stick) Suit

From left to right, the tiles have values 1 to 9. There are 4 tiles for each value.

The Winds and Dragons (collectively called Honors)

The first 4 are wind tiles that correspond to the 4 directions: East, South, West, and North. There are 4 for each of these tiles. This is also the order players' seats are named on the MahJong table: starting from the dealer being East, rotating counterclockwise up to North.

The last 3 are dragon tiles, again there are 4 of each.

The Flowers

All the flower tiles are distinct. They are not normal tiles and play relatively minor roles in MahJong, mostly to introduce the factor of "luck". Some versions don't even use them, but we do.

Sets of Tiles

• A pair is a set of 2 identical tiles.
  For example: or .
• A sequence is a set of 3 tiles of the same suit, in consecutive values.
  For example: or . Note that you cannot form a sequence with word tiles.
• A triplet is a set of 3 identical tiles.
  For example: or .
• A quadruplet is a set of 4 identical tiles.
  For example: .

Games and Rounds

If the dealer wins the game or if the game is a draw, then he remains the dealer for the next game. However, if someone other than the dealer wins the game, then the next player in turn (who used to be South) will be the dealer for the next game.

When the dealer has rotated a full round back to the very first one, the round wind rotates to the next one in the wind tiles.

A MahJong Game

To draw a tile, a player takes a tile from the stockpile on the table. If it is a flower, he reveals it and keeps drawing until he gets a normal tile. NB: in normal games, players draw tiles from the beginning or the end of the stockpile depending on the situation. We don't make that distinction in IMS.

Initially, each player draws 13 tiles. The dealer draws a 14th one, and the game starts, the dealer having the turn.

The player in turn has the following options:

• Discard a tile.
  To do this in IMS, click on that tile, and press [Discard].
• Form a quadruplet if he has 4 identical tiles in his private hand. Thus he makes a concealed quadruplet: the set of quadruplet has revealed status, but the other players cannot see them until the game ends. The player then draws another tile to compensate for the quadruplet.
  To do this in IMS, click on one of the 4 tiles, and press [Kong x4].
• Form a quadruplet if he already has a revealed triplet and now has a 4th tile of the same kind. This play may put the player at the risk of feeding another player's winning hand and count as a robbing quadruplet. If the play is safe, then the player makes a revealed quadruplet, and draws another tile to compensate.
  To do this in IMS, click on the 4th tile, and press [Kong x4].
• Win the game, if he has a winning pattern.
  To do this in IMS, simply press [MahJong].

For the immediate successor (in counterclockwise order) of the player who just made the discard, he has the following choices:

• Bid to draw another tile.
  To do this in IMS, press [Draw].
• Bid to make a sequence with the discarded tile and 2 other tiles in his private hand.
  To do this in IMS, press one of the 3 corresponding [Chow] buttons.
• Bid to make a triplet with the discarded tile and 2 same tiles in his private hand.
  To do this in IMS, press [Pong x3].
• Bid to make a quadruplet with the discarded tile and 3 same tiles in his private hand.
  To do this in IMS, press [Kong x4].
• Bid to win the game (with a winning pattern) after grabbing the discarded tile.
  To do this in IMS, press [MahJong].

• Bid to pass, i.e. do nothing.
  To do this in IMS, press [Pass].
• Bid to make a triplet with the discarded tile and 2 same tiles in his private hand.
  To do this in IMS, press [Pong x3].
• Bid to make a quadruplet with the discarded tile and 3 same tiles in his private hand.
  To do this in IMS, press [Kong x4].
• Bid to win the game (with a winning pattern) after grabbing the discarded tile.
  To do this in IMS, press [MahJong].

Bids have the following order of precedence:
pass < draw & sequence < triplet & quadruplet < MahJong.

If the table allows multiple wins, then all players who claims MahJong win the game. Otherwise, only the closest successor (in counterclockwise order) of the player who just made the discard wins. The player who just made the discard is the feeder.

If nobody wins, the player who has the highest bid makes his play:

• If his bid is draw, he draws a tile from the stockpile. The game is declared a draw (i.e. nobody wins) if the stockpile has less than 14 tiles.
• If his bid is sequence or triplet, he forms a new revealed set with the discarded tile and his 2 other tiles.
• If his bid is quadruplet, he forms a new revealed set with the discarded tile and his 3 other tiles, then draws another tile to compensate.

After someone wins the game, or if the game is a draw, the dealer, round wind and seat winds are rearranged (see Games and Rounds) and a new game starts.

IMS Table Options

• Use Flower Tiles. This option controls whether or the table will use flower tiles. If used, the possession of them may result in more scores. See the Scoring System for details.
• Allow Multiple Wins. There are rare occasions when one player discards a tile that makes 2 or even all 3 of the other players complete a winning pattern. In some conventions, only the nearest successor (in counterclockwise order) of that player can win, whereas in other conventions, all the players with a winning pattern can win.
• Stricter MahJong. When on, a player cannot win by grabbing a tile that he has discarded. If he choose to let a discarded tile "slip by" without declaring MahJong, he cannot declare MahJong on the same tile before the turn-to-discard passes through him.
• Minimum Fan. The minimum fan value required in order to declare MahJong. This fan value does not include adjustments from the aux value.
• Invitation Only. For some privacy. Spectators cannot be blocked out. IMS is a social center after all!

IMS Scoring System

Some terminologies first:

• A Concealed Set consists only of tiles that originated in a player's private hand. Includes Concealed Quadruplets.
• A Revealed Set consists of a grabbed tile.
• A Fully Private Hand must not have any Revealed Sets prior to declaration of MahJong. Such a hand can contain Concealed Quadruplets, and can be obtained by grabbing a discard or robbing a kong.

• Dragon Sets:
  * For each Triplet or Quadruplet of the dragon tiles: 1 point.
• Wind Sets:
  * For each Triplet or Quadruplet of the player's Seat Wind or game's Round Wind (if applicable): 1 point.
  * For each Triplet or Quadruplet of a wind that is both Seat Wind & Round Wind: add 1 more point.
• All Sequences:
  * Hand is Fully Private & consists of 4 Sequences: 1 point.
  
• Equal Sequences in three suits:
  * Hand contains 3 Sequences in 3 different suits with the same values: 1 point.
  * Hand is Fully Private: add 1 more point.
• Straight Sequences:
  * Hand with 3 Sequences in same suit with the values [1, 2, 3], [4, 5, 6] & [7, 8, 9]: 1 point.
  * Hand is Fully Private: add 1 more point.
• Sister Sequences:
  * Hand is Fully Private with 2 Sequences of the same suit & with same values: 1 point.
  * With 2 such Sister Sequences: add 2 more points.
• No terminals:
  * Hand does not contain any 1's or 9's or honour tiles: 1 point.
• All terminals:
  * All 4 Sets & the Pair contain 1's or 9's or honour tiles: 1 point.
  * All 4 Sets are Triplets or Quadruplets: add 1 more point.
  * None of tiles an honor tile: add 1 more point.
  * Hand is Fully Private: add 1 more point.
• Totally concealed:
  * Hand is both Fully Private & Self-feeding: 1 point.
• Totally revealed:
  * Hand with 4 Revealed Sets (i.e. no Concealed Quadruplets), & Pair formed by picking up discarded tile: 1 point.
• Under the sea:
  * Hand formed by drawing the last tile from the Wall: 1 point.
• Under the river:
  * Hand formed by picking up a discarded tile, and when the Wall is out of tiles: 1 point.
• Winning after a kong:
  * Hand formed after drawing a tile from the end of the Wall, following a Kong: 1 point.
• Robbing a kong:
  * Hand formed by picking up the 4^th tile of a kong that makes a Revealed Quadruplet: 1 point.
• All Triplets:
  * Hand with 4 Triplets and/or Quadruplets: 2 points.
• 7 little pairs:
  * Fully concealed Seven-Pair Mahjong Hand (i.e. there can be no Concealed Quadruplets, but may contain 4 identical tiles counted as 2 Pairs): 3 points.
• Equal Triplets in three suits:
  * Hand containing 3 Triplets and/or Quadruplets in 3 suits of same value: 2 points.
• 3 Quadruplets:
  * Hand contains 3 Quadruplets: 2 points.
• 3 Concealed Triplets:
  * Hand with 3 Concealed Sets that are Triplets and/or Quadruplets: 2 points.
• (Mixed) One Suit:
  * Hand with only tiles from one suit plus possibly honor tiles: 2 points.
  * Hand has no honor tiles ("Pure one suit"): add 3 more points.
  * Hand is Fully Private: add 1 more point.
• Minor 3 dragons:
  * Hand contains a Pair plus 2 Triplets and/or Quadruplets of dragon tiles: 2 points.
• Major 3 dragons:
  * Hand contains 3 Triplets and/or Quadruplets of dragon tiles: 12 points.
• Minor 4 winds:
  * Hand contains a Pair plus 3 Triplets and/or Quadruplets of wind tiles: 12 points.
• Major 4 winds:
  * Hand with 4 Triplets and/or Quadruplets of wind tiles: 12 points.
• Pure 1's & 9's:
  * Hand in which all tiles are 1's or 9's: 12 points.
• Pure honor tiles:
  * Hand in which all tiles are honor tiles: 12 points.
• 4 Quadruplets:
  * Hand with 4 Quadruplets: 12 points.
• 4 Concealed Triplets:
  * Hand with 4 Concealed Sets that are Triplets and/or Quadruplets: 12 points.
• 9 lanterns:
  * Fully Private hand with all tiles from one suit, containing the 13 values [1, 1, 1, 2, 3, 4, 5, 6, 7, 8, 9, 9, 9], plus any other value: 12 points.
• All green tiles:
  * Hand with only tiles in the bamboo suit with values 2, 3, 4, 6, 8, and/or the Fa (green) dragon tile: 12 points.
• "13 Individuals":
  * Strictly (1 4 7), (2 5 8), (3 6 9) in 3 different suits, plus 3 words and a distinct word pair: 5 points.
• "13 Orphans":
  * 6 different 1's and 9's plus 7 different words, plus another of the above 13: 12 points.
• "Heavenly/Earthly/Humanly MahJong":
  * Getting MahJong in the first ciruclation of the game: 12 points.

The aux value is the sum of all points from applying the following rules to the Set(s) and Pair(s) in the hand.

• Each revealed quadruplet: 1 point.
• Each concealed quadruplet: 2 points.
• If the use flower tiles option is on, each flower tile: 1 point.

• if aux < 2, do nothing.
• if 2 <= aux < 4, add 0.5 to fan.
• if aux >= 4, add 1 to fan.
• fan should not to exceed 12.

The Hand's Basic Score is give by the following table:

Adjusted Fan	0	0.5	1	1.5	2	2.5	3	3.5	4	4.5	5	5.5	6
Basic Score	4	4	8	12	16	24	32	40	52	64	76	84	92
Adjusted Fan	6.5	7	7.5	8	8.5	9	9.5	10	10.5	11	11.5	12
Basic Score	96	100	104	108	112	116	120	124	124	128	128	132

The hand's Total Score is a multiple of its basic score, the multiplier given by the following:

	Non-dealer	Dealer
Win on grab	1.0	1.5
Self-feed	1.5	1.5

Points are allotted from non-winning players to each of the Winners separately. Each Winner always receives his Total Score many points. In addition points will be deducted from non-winners and credited to winners according to the following rules, which are to be checked in the order given, i.e. the first applicable rule encountered is the one applied.

• Winner made 4 chows: Winner made 4 chows in his/her Mahjong Hand: the player to winner's immediate left who "supplied" the 4 chows pays Winner's entire Total Score to the Winner, regardless of self-feeding or who the feeder is.
• Winner had Major 3 Dragons: Winner had Major 3 Dragons Mahjong Hand and all 3 dragon-tile Sets came from picking up discarded tiles: the player making the 3^rd of said discards pays Winner's entire Total Score to Winner, regardless of self-feeding or who the feeder is.
• Winner had Major 4 Winds: Winner had Major 4 Winds Mahjong Hand and all 4 wind-tile Sets came from picking up discarded tiles: the player making the 4^th of said discards pays Winner's entire Total Score to Winner, regardless of self-feeding or who the feeder is.
• Self-feeding win: the other 3 players each pay Winner 1/3 of Winner's Total Score.
• Win on grab: the feeder pays Winner the Winner's full Total Score.