Ryuukyoku 「流局」 is also known as an exhaustive draw. Sometimes, all the tiles aside from the dead wall are drawn; and no player manages to produce a winning hand. Points are exchanged based on the number of players with a tenpai hand vs those who are in noten (not tenpai).
In this case, players in tenpai' reveal their hands and receive points from those in noten. Players in noten may choose to reveal their hands, but it is not required. Noten hands do not affect the point exchanges, when revealed. Though, players in tenpai are not particularly required to reveal their hands. Instead, they may opt to declare noten, despite having a tenpai hand. In exchange for keeping the hand hidden, a player loses points.
Wind seating may or may not occur depending on the dealer's hand. If the dealer is tenpai, then the wind seating does not rotate; and on the other hand, wind seating does rotate if the dealer fails to develop a tenpai hand. Though rules may be modified to require the dealer to win the hand, rather than just simply attaining tenpai.
While the term "ryuukyoku" is usually used to refer to an exhaustive draw in Japanese, on occasion this may be ambiguous, as the term technically refers to any draw (cf. tochuu ryuukoku, 「途中流局」). When ambiguity occurs, it may be referred to as tsuujou no ryuukyoku 「通常の流局」, which translates roughly as "usual kind of draw".
Tenpai is the state of the hand waiting on just one tile to claim for a win, either by draw or discard. Even if the hand does not win, it can still be awarded a small amount of points at the end of the hand, after all possible tiles are drawn and discarded. So, hands at tenpai during ryuukyoku still has some value.
If some players are tenpai and some are not, a total exchange of 3,000 points are evenly split between the players in tenpai players from the players in noten.
Point exchanges are as follows:
- 0 players in tenpai: No points exchanged.
- 1 player in tenpai: All players in noten pays 1,000 points to the tenpai player.
- 2 players in tenpai: Each player in noten pays 1,500 points, each player in tenpai receives 1,500 points.
- 3 players in tenpai: The single player in noten plays 1,000 points to each player in tenpai.
- 4 players in tenpai: No points exchanged.
When no players are in tenpai, then the wind seating rotates. When all players are tenpai, then the wind seating does not rotate. For the other three cases, wind rotation is dependent on the dealer being tenpai or not. When a ryuukyoku occurs, a honba is added to the count for the next hand, with two exception: when a player in riichi reveals a noten and is penalized for chombo and, in some variations of the nagashi mangan rule, when a player successfully completes nagashi mangan.
Sometimes, the ryuukyoku point exchanges is enough to determine the final position in games, especially in oorasu (the last hand). Dealers in tight point races need to take particular note about the need to attain tenpai or allow the game to end. It may be desirable to pass on a small winning hand in order to collect the payment from noten players instead.
Often, a hand may end in a draw, where players had declared riichi. Any leftover riichi bets on the table are placed near the counters until collected by the winner of a hand. If the dealer is not in tenpai, then the seat winds rotate normally. If the dealer is in tenpai, the seat winds remain the same for the next hand.
The count for honba keeps track of the number of consecutive hands, by which no one has won a hand. Every time ryuukyou or even tochuu ryuukyoku (abortive draw) occurs, this count increases by one. Barring house rules, the count may or may not increase regarding chombo. When a non-dealer player wins a hand, the count resets back to zero.
Variation on ryuukyoku stems from the qualification of tenpai. Under some rules and conditions, some hands may be declared as noten instead, even if they appear to be in tenpai.
Some many consider this hand as noten, despite needing one tile for completion. However, that one tile is one among the tiles called for a closed kan by the same player. The hand is also karaten, or impossible to complete. All possible tiles for completion are used with the dubious kan call. So, instead of gaining points, the player loses points at ryuukyoku.
At some point, the hand looked like this. As it stands, this hand is actually complete. The kan was closed, and no open call was made. The tiles already constitute the necessary tile groups and the pair. Therefore, the hand should have been properly called for a win or tsumo instead.
- Ryuukyoku in Japanese Wikipedia