The goal of the game
Riichi mahjong is played by four people. A hand normally contains thirteen tiles between turns; East starts every hand with fourteen tiles and discards first. A declared kan adds one physical tile while occupying one group slot. The goal is to complete a valid hand before the other three players.
The ordinary form has four groups and a pair. Each group is a run, a triplet or a declared kan, which contains four tiles but occupies one group slot. Two special forms also exist: seven pairs and thirteen orphans. A complete shape is not enough: the hand must contain at least one yaku to win.
A game runs over several hands. When a player wins, payment comes from the opponents; the final score ranking decides the game. It is a game of incomplete information where efficiency and defense matter as much as luck.
The tiles
The game uses 136 tiles: three number suits (man characters, pin circles, sou bamboo), numbered 1 to 9 in four copies each, plus the honors (the four winds and three dragons). The Tenhou profile uses one red five in each suit.
A group is either a run of three consecutive numbers in one suit or a triplet of three identical tiles. Honors cannot form runs. The final pair can be any two identical tiles.
The table, the seats and a turn
The four seats carry a wind name: East, South, West, North. East is the dealer and goes first. On their turn a player draws a tile from the wall and discards one, placing it face up in their river (the kawa). Play rotates counter-clockwise.
A player's discard can be claimed by another to complete a group, which interrupts the turn order. Otherwise the hand continues until someone wins or the wall runs out.
Calls: chi, pon, kan
Claiming a discard is called a call. Pon takes a tile to form a triplet and can be made on anyone’s discard. Chi completes a run and can only be made on the discard of the player to your immediate left. Daiminkan claims a discard to gather all four copies of a tile.
Chi, pon and daiminkan open the hand; after an ankan made from four tiles in your own hand, the hand retains its closed status. Every completed kan grants a replacement draw from the dead wall. Kan-dora is revealed immediately for an ankan, then after the discard for a daiminkan or shouminkan.
Winning: you need a yaku
Completing four groups and a pair is not enough: a winning hand must contain at least one yaku, a named pattern defined by the rules. Without yaku the shape may be valid, but it is not a winning hand and no win may be declared.
You win in two ways: by tsumo, drawing the winning tile yourself, or by ron, claiming the tile an opponent just discarded. A closed-hand tsumo is itself a yaku (menzen tsumo). Outside pao liability on certain yakuman, ron is paid only by the player who discarded the tile.
Riichi
When a closed hand is in tenpai, its player may declare riichi by placing a 1000-point deposit. Under Tenhou, the player must hold the deposit and retain another draw, represented by at least four tiles in the live wall. A ron on the declaration discard voids that riichi and returns its deposit. A valid riichi is a yaku and unlocks uradora.
After riichi, every drawn tile must normally be discarded unless it completes the hand. An ankan remains legal with the tile just drawn if the wait does not change; hand interpretation and yaku may change. Passing a tile that completes a valid winning shape imposes furiten for the rest of the hand, even if that shape has no yaku.
Scoring: han, fu and dora
An ordinary hand's value is measured in han and fu. Ordinary yaku and dora add han; fu count structural points from value pairs, triplets, kan, wait shape and how the hand was won. The score is computed from those two numbers, with value rising sharply as han grows. Genuine yakuman instead use a fixed payout.
Dora are bonus tiles marked by an indicator: in an ordinary hand, each adds a han but is never a yaku; they are not counted on a genuine yakuman. The tiers are mangan, haneman, baiman and sanbaiman. Tenhou does not use kiriage mangan; from 13 han onward, the hand becomes a kazoe yakuman.
Genuine yakuman are specific patterns. Different yakuman present in one hand stack under Tenhou; special waits remain single value.
Furiten and defense
Furiten forbids winning by ron if one of your waiting tiles already sits in your own discards; only tsumo remains. Under Tenhou, passing a tile that completes a valid shape, even without yaku, creates temporary furiten until your next discard. Your own call does not clear it immediately. After riichi, that ban lasts for the rest of the hand.
Defending means avoiding dealing into (deal-in) an opponent’s hand. A tile already in an opponent’s discards (genbutsu) is safe against them, and suji reasoning helps gauge the danger of the rest. Folding in time is often worth more than pushing.
The end of the game
If nobody wins before the wall is exhausted, the hand is a draw: tenpai players share 3000 points paid by noten players. East keeps the deal after a win or a tenpai draw. One honba is added after every East win and every exhaustive draw.
A tonpuusen schedules the East round and a hanchan the East and South rounds. Under Tenhou, everyone starts on 25,000 points with a 30,000 return, oka and 20-10 uma. A game may extend into South or West if nobody reaches 30,000, but ends when a score becomes negative. All five abortive draws, nagashi mangan and double ron are active; triple ron aborts the hand. Riichi deposits left at match end go to the leader.
The main WRC 2025 differences
Tenpai.gg teaches the Tenhou profile first. Under WRC 2025, everyone starts at 30,000 points with no oka and +15, +5, -5, and -15 uma. There are no red fives, West round, bankruptcy ending, agari yame, or tenpai yame. Only one ron is paid by turn order, and riichi deposits left at match end go to nobody.
WRC 2025 allows riichi below 1,000 points and on the final live-wall tile. Temporary furiten ends on the player’s next draw or own call. Every kan reveals its new indicator before the discard, and an ankan after riichi must preserve both structure and wait.
For scoring, WRC 2025 applies kiriage mangan to 4 han 30 fu and 3 han 60 fu, limits a double-wind pair to 2 fu, calls the ordinary 13-han tier yonbaiman, adds 5-han renhou, and extends pao to suukantsu.