Riichi: Difference between revisions

'''Riichi''' {{kana|立直}} or {{kana|リーチ}} is the most commonly used [[List of yaku|yaku]] in the game. This yaku may apply to any closed hand and may be declared upon achieving ''[[tenpai]]''. Due to its common usage, various specific game scenarios must be considered when using riichi.

When a player has a closed ''tenpai'' hand, the player may declare riichi.  Doing so gains the hand 1 han.  To declare riichi, a player announces riichi and discards a tile facing sideways in the discard pile.  This is done to indicate when riichi was called.  If that tile is claimed by another player for an open meld, then the next discard is turned sideways as a replacement.

Unless the first sideways discard is claimed for a win immediately, the riichi announcer now places a bet of 1,000 points on the table. This bet is collected by the next player to win a hand. Specific rulesets may handle differently what happens to the bet on a multiple win.

After a riichi declaration, the hand remains locked and unchangeable. In this state, the player is simply waiting for a winning tile to appear, either by draw or discard.

It is not allowed to declare riichi when less than four tiles remain in the wall. The player must be able to draw one more tile in an uninterrupted set of turns.  The absolute last chance to call riichi is when the player has a chance to score riichi, [[haitei]], [[ippatsu]], and [[mentsumo]]. [http://tenhou.net/0/?log=2013062617gm-0089-0000-xa37799b6321c&tw=3&ts=4 Example].

=== Ippatsu ===

'''Ippatsu''' {{kana|一発}} is awarded if the player receives a winning tile within an uninterrupted set of turns after the riichi declaration. Tile calls interrupt the set of turns. The latest possible chance to win with ippatsu is with the player's next drawn tile after the riichi declaration.  In turn, this yaku may only be scored with riichi and is worth an additional 1 han, in conjunction with riichi.

[[Naki|Tile calls]] may disrupt the chance for ippatsu any time before the riichi declarer draws the next tile.

=== Double riichi ===

'''Double riichi''' {{kana|ダブルリーチ}} is a special case for riichi, where the player declares riichi on the first turn. No tile call may have interrupted the turn order before the declaration, where applicable.  Double riichi is worth 2 han instead of 1 han, as a bonus for the initial timing.

=== Kan during riichi ===

{{main|Kan}}

When a riichi declarer holds three identical tiles and draws the fourth after the riichi announcement, he may form an [[Kan|ankan]] from these tiles instead of discarding the fourth. The hand composition and the possible winning tiles may not change: It is not allowed to declare kan if, for some possible winning tile, any of the three identical tiles may be interpreted as part of a shuntsu or part of the pair.

:{{#mjt:3444m 778899s 333z}}, draw: {{#mjt:4m}}.

:{{#mjt:111m222333p5678s}}, draw: {{#mjt:1m}}, {{#mjt:2p}}, or {{#mjt:3p}}.

=== Furiten ===

If a riichi declarer does not win at first opportunity, he will be permanently [[Furiten|furiten]].  All tiles discarded after the riichi declaration, as indicated by the discarded sideways tile, are considered to be guaranteed [[genbutsu|safe tiles]].

=== Ura dora ===

{{main|Dora}}

When a riichi declarer wins, he may flip the tiles underneath the [[dora]] and kan dora indicators. These flipped ''ura dora indicators'' may increase the value of his hand.

=== Tochuu ryuukoku ===

Tochuu ryuukoku, or abortive draw, is in effect when suucha riichi occurs.  In this case, three riichis have been called; and a fourth one is called in place.  If the discarded tile is not claimed for a win, then the hand ends.

{{main|Yaku compatability}}

| RCH ||bgcolor="000000"| ||bgcolor="000000"|  || {{yes}} || {{yes}} || {{yes}} || {{yes}} || {{yes}} || {{yes}} || {{yes}} || {{yes}} || {{yes}} || {{yes}} || {{yes}} || {{yes}} || {{yes}} || {{yes}} || {{yes}} || {{yes}} || {{yes}} || {{yes}} || {{yes}} || {{yes}} || {{yes}} || {{yes}} || {{yes}} || {{yes}}

| DRI ||bgcolor="000000"| ||bgcolor="000000"|  || {{yes}} || {{yes}} || {{yes}} || {{yes}} || {{yes}} || {{yes}} || {{yes}} || {{yes}} || {{yes}} || {{yes}} || {{yes}} || {{yes}} || {{yes}} || {{yes}} || {{yes}} || {{yes}} || {{yes}} || {{yes}} || {{yes}} || {{yes}} || {{yes}} || {{yes}} || {{yes}} || {{yes}}

|-

Given the rules, riichi is compatible with all other yaku. Likewise, riichi and double riichi cannot be combined as they are essentially the same yaku. It just happens that double riichi is a specific instance of riichi.  As for ippatsu, per rule, it is impossible to attain ippatsu without riichi.

Once again, the prospect for [[rinshan kaihou]] to work with riichi is dependent on the legality of the [[Riichi#Kan_during_riichi|kan call during riichi]].  With computer interfaces, this rule may be enforced by disabling a player's ability to call the kan during this situation.  However, with actual tiles, a player must be aware of this legality.

== Strategy ==

* Riichi is an automatic yaku and is eligible to count for 1 additional han (after a win).

* Access to the [[dora|ura-dora]] (after a win).

* Kans formed by any player provide two extra dora indicators for the riichi declarer instead of one.

* Other players are recommended to defend against riichi calls, if possible or needed.  Otherwise, players run the risk of falling to that hand.

* Other players still have the option to develop their hands and potentially "snipe" the hand.  [http://tenhou.net/0/?log=2012111209gm-0009-7447-x33034e7e5279&tw=2&ts=4 Example].

* It is highly recommended to declare the win on the first instance of a winning tile, even if the tile is a [[yasume]] or a lower scoring tile (based on yaku).  Otherwise, the hand is subject to [[furiten]].  A riichi call disables a person's ability to be [[targeting|selective]] of points from particular players (if need be).

 

Once again, riichi is a discretionary play.  In fact, in all instances of considering and calling riichi, risk is involved.  Therefore, various factors must be considered before employing using riichi.  At the same time, many plays involving riichi are highly recommended.  Employing riichi is a matter of the current game state.  Now, here are some questions to consider:

 

<!-- Likewise, feel free to add some questions for consideration -->

* '''What game round is it?'''

* '''Is the lead currently held? Is said lead significant, or close to second place?'''

* '''Is it necessary to improve the hand by calling riichi?'''

* '''Would [[damaten]] be sufficient?'''

'''Oikake riichi''' (追いかけリーチ) is a declared riichi, after another player had already declared riichi.  In this state, two or even three players have simultaneously declared riichi; and thus, the game becomes a contest between two or three tenpai hands.  In this state, any riichi declarer is liable of playing into another's riichi call.

 

The process of four active riichi hands is not possible due to ''[[Tochuu ryuukoku|suucha riichi]]'', or four called riichi.  In this case, the hand ends if the fourth riichi discard is not a winning tile for any of the previous three.

*[https://ja.wikipedia.org/wiki/一発 一発]

:Ippatsu in Japanese Wikipedia.

*[https://ja.w*ikipedia.org/wiki/ダブルリーチ ダブルリーチ]

:Double riichi in Japanese Wikipedia.  

[[Category: Yaku]]