Ryuukyoku

Ryuukyoku 「流局」, or exhaustive draw, is a way of ending a hand. It occurs when all the tiles (excluding those in the dead wall) have been drawn, and no player manages to produce a winning hand. After the player with the last tile draw makes a discard, if no one claims a win, then the hand simply ends in "exhaustive draw". During an exhaustive draw:

  • Players in tenpai reveal their hands, then receive points from players who are in noten (not tenpai).
  • Wind seats may rotate, depending on the dealer's hand and the ruleset.
    • If tenpai renchan is enabled, seats do not rotate if the dealer is tenpai, seats do rotate.
    • If tenpai renchan is disabled, seats rotate regardless of the dealer's hand status.
  • The honba count increases by 1.
Point exchange at ryuukyoku.

Afterwards, a new hand starts. 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 ryuukyoku, 「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".

Rule overview

Unless a chombo occurs, the following happens during an exhaustive draw:

Point Exchanges

If some players are tenpai and others are not, points are exchanged. The players in noten pay a combined sum of 3000 points, split between players in tenpai. This results in the following score table:

  • 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 pays 1,000 points to each player in tenpai.
  • 4 players in tenpai: No points exchanged.

If a player qualifies for nagashi mangan, all point exchanges from tenpai are skipped. Instead, players pay a "mangan tsumo" to the players with nagashi mangan. The dealer pays 4000 points and other non-dealers pay 2000 points to each non-dealer with nagashi mangan; all non-dealers pay 4000 to the dealer with nagashi mangan.

Any riichi bets left on the table are saved for later rounds. The next player that wins claims all leftover riichi bets.

Players in noten are not required to reveal their hands. When playing with physical tiles, players in tenpai may (intentionally or not) declare noten, losing out on the tenpai points.

See the Tenpai section below for the general definition of "tenpai" used by ryuukyoku.

Seat rotation

Wind seat rotation is dependent on the dealer's hand state and the ruleset.

  • Agari renchan: Seats are kept only when the dealer wins. This means that, during an exhaustive draw, seats rotate regardless of the dealer's tenpai status.
  • Tenpai renchan: Seats are kept when the dealer wins, or if the dealer is tenpai at exhaustive draw. This means that, during an exhaustive draw, seats rotate only if the dealer is noten.

Regardless of wind rotation, after an exhaustive draw, the honba count increases by 1.

Tenpai

Tenpai is the state of the hand waiting on just one tile to claim for a win, either by draw or discard. When an exhaustive draw happens, a win is no longer possible, but a small point bonus is given.

Karaten

 
An ankan case called as tenpai in Majsoul.

A hand may be in tenpai but be unable to win in the actual game. For example, all the winning tiles could've been discarded before reaching tenpai. This is known as karaten.

Whether such hands count as tenpai depends on rule variation. Under many rulesets:

  • A hand with no yaku counts as tenpai for ryuukyoku.
  • A hand in furiten counts as tenpai.
  • A hand with all possible winning tiles discarded (or otherwise unavailable) counts as tenpai.
  • A hand with all possible winning tiles in the player's own hand (see below) does not count as tenpai.

For an example of the last case:

               

Despite the hand being one tile away from completion, all of the possible winning tiles are in the player's own closed kan. So, instead of gaining points, the player is considered noten. (However, this, like the other points, is subject to rule variation.)

Chombo

A player is not allowed to call a riichi without tenpai. If a player declares noten riichi, and the hand ends in ryuukyoku, the player is penalized for chombo.

No wind rotation is applied, and no point exchanges are applied. The honba count is not increased. The next hand continues as if the chombo hand did not even occur. Of course, the appropriate penalty for chombo is applied and the game continues.

Strategy

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.

Since players often abandon the hand after a player declares riichi, the exhaustive draw rate is quite high in professional play:

  • Around 15.5% of Tenhou hands in the Houou lobby go to an exhaustive draw.[1]
  • Around 23.5% of M League hands in the 2022-2023 regular season went to an exhaustive draw.[2]

References

  1. https://pathofhouou.blogspot.com/2019/08/analysis-average-houou-game.html
  2. https://web.archive.org/web/20230605101538/https://m-league.jp/stats/?season=L001_S013
    While the exhaustive draw rate is not displayed, it can be calculated. Since M League uses atamahane and does not have abortive draws, all games either end in a win or an exhaustive draw. Therefore, (average win rate * 4) + (exhaustive draw rate) = 100% of games. The average win rate is 19.125%, so the exhaustive draw rate is 23.5%.

External links

Ryuukyoku in Japanese Wikipedia