1. Introduction
Mahjong Competition Rules (MCR), often called Chinese Official, is the international competition rule set for mahjong published by the World Mahjong Organization. Its distinguishing feature is a large catalogue of scoring patterns and a minimum score of eight points before a hand may be declared a win (3.4.22, 3.9.1).
The rule system is intended to spread an Olympic-style spirit and promote friendship and cultural exchange, and it applies to contests hosted by the World Mahjong Contest Center and approved by the World Mahjong Organization, to contests hosted by member countries, and to others adopting it (1.1.1, 1.2.1). Power of interpretation belongs to the World Mahjong Contest Center (1.2.3).
This summary follows the 2014 English edition (11 April 2014). It supersedes the widely circulated 2006 edition known as the "Green Book": the 2014 text carries 112 numbered clauses against the 2006 text's 75, and revises many of the shared ones — including the scope of the rule system, the terminology for officials, and the procedure for seating.
2. Components
Tile Types
- Honor tiles are the winds and dragons taken together. There are four Wind Tiles — East, South, West, North — and three Dragon Tiles — White, Red and Green — with four of each (3.4.15)
- Terminal tiles are the ones and nines of a suit, together with the honor tiles (3.4.16)
- Flower tiles are used: a player who draws one may expose it and take a replacement tile from the back end of the wall, repeating until no flowers remain in hand (3.4.20)
Groupings
- Chow — three sequentially-numbered tiles of the same suit (3.4.12)
- Pung — three identical tiles, concealed or melded (3.4.13)
- Kong — an exposure of four identical tiles; also the meld itself (3.4.19)
- Pair — any two identical tiles (3.4.14)
The Hand
- A player holds thirteen tiles after the deal, including any melded chows, pungs and kongs (3.4.10)
- Those thirteen do not include kong replacement tiles or flowers (3.4.10)
- Tiles not yet melded when mahjong is declared are concealed; standing tiles are the concealed tiles a player has not discarded (3.4.10)
3. Setup
Table and Seating
- Four players per table, each table playing as an independent group (3.5.2)
- Seating is the placement of players around the table by table number, determined by drawing lots or arranged in advance under the tournament regulations (3.4.7)
- Lots are drawn publicly, fairly and impartially; where a team is absent the organizing committee appoints someone to draw in its place and the lot stands (3.5.1)
- Seat allocation may also avoid seating players from the same country or region at one table (3.5.1)
Winds
- The seat wind marks each player's seat: the dealer is East, the player to the dealer's right is South, opposite is West, and to the dealer's left is North (3.4.6)
- The prevalent wind names the round — the first round is East, then South, West and North (3.4.5)
Units of Play
- A go-around (lun) is complete when everyone has discarded once in turn (3.4.1)
- A hand (pan) is everything between a deal and either a declaration of "Hu" or nobody winning — a draw game (3.4.2)
- A round (quan) ends when everybody has been dealer once; there are four rounds in a complete game (3.4.3)
- A complete game (ju) is four rounds, or in a tournament the time allotted for them; it may also be called a session (3.4.4)
4. Gameplay
Calls Must Be Spoken
- Every claim on a discard must be verbalized (3.6.1)
- Say "Chi" to chow, "Pung" to pung, "Kong" (or "Gang") to kong, "Hu" to declare mahjong, and "Hua" when taking a flower replacement (3.6.1)
- Players must not call out the names of tiles when discarding, and are forbidden to discuss, gossip, or communicate in their own or another language (3.6.1)
The Turn
- Play consists of taking a tile, discarding, and the claims — chow, pung, kong — in the prescribed order of turns (3.6.2)
- A player is waiting when a single tile would complete their hand (3.4.21)
- A flower replacement is drawn from the back end of the wall, repeated until the hand holds no flowers (3.4.20)
Declaring a Win
- Winning (hu) is reached when, after taking a discard or drawing, the fourteen tiles form a complete structure as prescribed and the hand scores eight or more points (3.4.22)
- Self-drawn — winning on a fresh tile taken from the wall (3.4.23)
- A hand that reaches neither a declaration nor a winner is a draw game (3.4.2)
5. Scoring & Winning
The Eight-Point Threshold
- Three conditions must all hold to declare "Hu": the hand is one of the permissible structures; its fan total at least 8 points; and the winning tile was obtained by a permitted method (3.9.1)
- The eight-point minimum is the defining constraint of MCR — a structurally complete hand that scores less is not a win (3.4.22, 3.9.1)
Fan
- There are 81 scoring elements (fan) in total (3.8)
- They fall into nine series: Honor Tiles; Number Tiles; Pungs; Seven Pairs; Tile Types Composition (flowers excepted); All Involved; Broken; Way of Making Mahjong; and Special (3.8)
- Point values reflect degree of difficulty, across twelve grades: 88, 64, 48, 32, 24, 16, 12, 8, 6, 4, 2 and 1 (3.8)
- More than one fan may be scored for a single winning hand (3.8)
- The highest grade includes patterns such as Big Four Winds — pungs or kongs of all four winds — and Big Three Dragons (3.8.1)
- The full catalogue with examples is Appendix 1 of the official rules; this summary gives the structure, not the 81 entries
Settling the Score
- A winning hand's points comprise Extra Points, Basic Points and Penalty Points (3.9.1)
- Scoring presupposes a declared win, and is recorded on the score sheet from the competition points as the calculating base (3.9.1)
- Players are ranked after competition under the ranking rules (3.10)
6. Variants & House Rules
MCR Compared with Riichi
- MCR and riichi are the two major competitive mahjong rule sets and are scored on entirely different principles: MCR counts fan against an eight-point threshold (3.8, 3.9.1), while riichi counts han and minipoints and has no equivalent minimum
- MCR uses flower tiles and flower replacement (3.4.20); riichi sets them aside entirely
- Both are recognised rule sets of the Mahjong International League
Which Edition Applies
- This summary follows the WMO 2014 English edition, the current text from the body that makes the rules
- The European Mahjong Association continues to name the 2006 "Green Book" as the reference for its MERS ranking tournaments, alongside its own Tournament Regulations and Referee Manual, official for MERS events since 1 January 2009. A European tournament may therefore be run under the older text
- Where the two differ, check the tournament's own announcement — the organiser states which edition governs
Competition Formats
- Events may be Individual, Team or Group Ranking (3.5.3)
- Three competition methods exist — Elimination, Round Robin and Mixed — and a tournament may use one and only one of them (3.5.4)