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→‎Open riichi: clarify: the yakuman rule is unrelated to "most professional games don't allow open riichi"

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 |gameExample = * [http://tenhou.net/0/?log=2013080615gm-0009-7447-xa503715f0f66&tw=3&ts=5 With ippatsu]
 * [http://tenhou.net/0/?log=2013053111gm-0009-0000-d06067c3&tw=1&ts=4 Three riichis called]
+* [http://tenhou.net/0/?log=2013101121gm-0009-7447-372f7d30&tw=3&ts=5 Ippatsu oikake riichi] with "[[dora|dora bomb]]"
+* [http://tenhou.net/0/?log=2012120515gm-0009-7447-637daef9&tw=3&ts=3 Double riichi]
 }}
-'''Riichi''' (立直 or 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.
+'''Riichi''' {{kana|立直}} or {{kana|リーチ}} is the most common [[List of yaku|yaku]] in the game, occurring in ≥40% of winning wands across various platforms and professional settings. Any closed hand that is in [[tenpai]] can choose to declare riichi, gaining this yaku.
+Declaring riichi is not mandatory. Players may decline to declare riichi, keeping the hand's tenpai status hidden - this is a tactic known as [[damaten]]. Various game scenarios should be considered before calling riichi, such as current point standing and available tiles.
 == Rules ==
+Riichi may be declared when:
+* The hand is closed - no [[chii]], [[pon]], or open [[kan]] has been made.
+* The hand is [[tenpai]] - it is one tile away from winning.
+* If the [[Rule_variations#Scoring|game ends when a player has a negative score]], the player must have at least 1,000 points.
+* There must be at least 4 tiles left in the live wall. In other words, the player must be able to draw at least one more tile in an uninterrupted set of turns.
+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 rules will differ on what happens if multiple players win, or what happens if the game ends before any player claims the bet.
+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.  However, there is a notable exception: a riichi player may declare [[kan]] in [[#Kan|certain circumstances]].
+In addition to the 1 han from riichi itself, you can score further han through [[#Ippatsu|ippatsu]] and [[#Uradora|ura dora]].
+=== Kan ===
+{{main|Kan#Kan during riichi}}
+Kan during riichi is a discretionary play. Players must take note of the hand composition to determine whether the kan is allowable or not. If the call alters the hand's waiting pattern or alters the hand's composition, kan is not allowed. Improper calls are subject to chombo if detected.
+=== Furiten ===
+{{main|Furiten}}
-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.
+During riichi, a player may be furiten.  In this case, the riichi is considered to be a '''furiten riichi'''.
-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.
+In addition, riichi hands are subject to a special type of furiten. After calling riichi, a player may decline to call on a winning tile. However, if a win is declined, then the riichi hand is subject to furiten for the remainder of the round.  Thus, all tiles discarded after the riichi declaration (as indicated by the sideways tile) are considered to be guaranteed [[genbutsu|safe tiles]]. While it is advised to declare a win on the first opportunity, some plays may require a player not to do so under very specific circumstances.  Of course, such play requires caution.
-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.
+=== Suucha riichi ===
+{{main|Tochuu ryuukyoku}}
-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.
+Suucha riichi (4 player riichi) is an [[abortive draw]] that occurs when four players have declared riichi. After the fourth riichi declarer discards a tile, if that tile is not called for a win, the hand ends.
-=== Ippatsu ===
+===Noten riichi===
-'''Ippatsu''' (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.  Ippatsu is a yaku worth 1 han.
+In real life play, a player may declare riichi without tenpai - this would be a '''noten riichi''' {{kana|ノテン立直}}, which is highly ill-advised. If the hand results in [[ryuukyoku]], then it is required to reveal the hand. The hand would naturally show noten, which is illegal, and thus subject to a [[chombo]] penalty.  Likewise, an incorrectly called win would also be subject to chombo. This dubious situation can be escaped if another player wins, another player commits a chombo, or if an [[abortive draw]] occurs. Of course, most computer based play will prevent players from declaring a riichi without tenpai.
-=== Double riichi ===
+== Scoring ==
-'''Double riichi''' (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 ===
+Two yaku are specifically associated with riichi: '''ippatsu''' and '''double riichi'''. In addition, '''ura dora''' may be scored for any winning riichi hand.
-{{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.
+=== Ippatsu ===
+{{main|Ippatsu}}
-Illegal example:
+'''Ippatsu''' {{kana|一発}} is a separate yaku, but it is dependent on riichi. If, after declaring riichi, the hand wins before the declarer's next discard, then the hand scores ippatsu. Any [[Naki|tile calls]], including a player's own closed [[kan]], will invalidate ippatsu.
-:{{#mjt:3444m 778899s 333z}}, draw: {{#mjt:4m}}.
-It is not allowed to kan the fours. The manzu tiles may either be interpreted as a 3-4 [[Ryanmen|ryanmen]] wait and a 4-4 pair, or as a 4-man ankou with a 3-man tanki wait. For a legal kan declaration, the three identical tiles would have to be an ankou in any interpretation. Had the player drawn a west wind, he would have been allowed to kan it.
+=== Uradora ===
+[[Image:Uradora.png|250px|right|thumb|The benefits of uradora. [http://tenhou.net/0/?log=2014070812gm-0009-7447-daa26980&tw=3&ts=9]]]
+{{main|Dora}}
-Legal example:
+When a riichi declarer wins, the tiles underneath the [[dora]] and kan dora indicators are flipped over. These flipped ''ura dora indicators'' reveal the ura dora, which, like regular dora, may increase the hands value.
-:{{#mjt:111m222333p5678s}}, draw: {{#mjt:1m}}, {{#mjt:2p}}, or {{#mjt:3p}}.
-=== Furiten ===
+=== Double riichi ===
+{{main|Double riichi}}
-If a riichi declarer does not win at first opportunity, he will be permanently [[Furiten|furiten]].
+'''Double riichi''' {{kana|ダブルリーチ}} is a special case for riichi.  If riichi is declared on the first turn, before the player's discard, then double riichi applies. In addition, no tile calls may have been made before riichi is called. As the name implies, double riichi is worth 2 han instead of 1 han, as a bonus for the initial timing. Due to the added han, and because tenpai is reached on turn 1, a double riichi hand has a huge advantage over others.
-=== Ura dora ===
+=== Open riichi ===
+'''Open riichi''' {{kana|オープン立直}} is an [[optional yaku]] which is a modified version of riichi. The mechanics are identical to a normal riichi, except that you must reveal either your entire hand or its tile [[wait]]s. In exchange, an open riichi is worth 1 extra han. Open riichi makes it trivial for other players to defend against your hand, so in general, the intent is to win by self-draw.
-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.
+As a further optional rule, yakuman may be awarded if any player intentionally [[ron|plays into]] the open riichi. If a player unintentionally deals in, i.e. if a riichi player deals into an open riichi, the yakuman is not scored.
-=== Tochuu ryuukoku ===
+Many official organizations and tournaments do not implement any form of open riichi; it is more or less reserved for casual or gambling game settings.
-{{main|Tochuu ryuukoku}}
+== Compatibility ==
+{{main|Yaku compatibility}}
-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.
+{{Yaku compatibility table|RCH,DRI}}
-== Strategy ==
+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.  Per rule and definition, it is impossible to attain ippatsu without riichi.
-Calling riichi is an optional play.  Therefore, players often have to make various considerations, when it comes to using riichi.  Often, this depends on the discarded tiles, how early or late in the hand, the hand value, and/or the player's hand composition.  If possible, a player may opt not to use riichi at all and instead employ the strategy of [[damaten]].
-=== Advantages ===
+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.  Otherwise, chombo may be enforced instead.
-* Any closed hand becomes eligible for winning by ron.
+=== Double riichi ===
-* Riichi is an automatic yaku and is eligible to count for 1 additional han (after a win).
+Double riichi has the same compatibility as riichi, except for [[chankan]]. This is because, for a regular hand, chankan may only be formed from an [[Kan#Shouminkan|added kan]], which itself requires a call for [[pon]] to happen first.
-* Kans formed by any player provide two extra dora indicators for the riichi declarer instead of one.
-* Access to the [[dora|ura-dora]] (after a win).
+* If the pon call happens before the riichi call, then double riichi is negated.
-* Other players are recommended to defend against riichi calls, if possible or needed.  Otherwise, players run the risk of falling to that hand.
+* If the pon call happens after the riichi call, then the double riichi player must have declined their winning tile, invoking [[furiten]]. Chankan can only be won from [[ron]], so furiten prevents chankan entirely.
-=== Disadvantages ===
+An exception is the yakuman [[kokushi musou]]. Depending on [[Kokushi_musou#Chankan_rule_variation|rule variation]], kokushi may be won off a [[ankan|closed kan]], which does not require a previous pon call. Therefore, in order to win with double riichi + chankan, it must also have kokushi. Since this would be a yakuman hand, the yaku of "chankan" is never actually scored.
-* It is less likely for opponents to deal in.
+== Strategy ==
-* By rule, the hand is locked.  Therefore, it is impossible to change the composition of the hand in order to get a better wait or an improved score.
+{{main|Riichi strategy}}
-* Likewise, a player can no longer defend and instead wait for a winning tile.
-* 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).
-== Oikake riichi ==
+Calling riichi is an optional play.  Therefore, players often have to make various considerations when it comes to using riichi.  Often, this will depend on the discarded tiles, how early or late in the hand, the hand value, and/or the player's hand composition.  If possible, a player may opt not to use riichi at all and instead employ the strategy of [[damaten]].
-'''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.
+=== Oikake riichi ===
+For any given hand, more than one player may call riichi.  Subsequent riichi calls after the first is called '''oikake riichi''' {{kana|追いかけリーチ}}, or "chasing riichi". Oikake has one distinct advantage of an ippatsu ron chance against any previous riichi hands before taking a draw.  After all, defense is no longer a factor to those hands, as they are committed to discarding non-winning tiles.  The hands are essentially engaged in a "riichi duel" provided that they have different waiting tiles. Under many rulesets, the hand aborts in the event for all players to have declared riichi via [[suucha riichi]].
-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.
+=== Karaten riichi ===
+Riichi may actually be called if all waiting tiles are rendered unavailable.  A hand in this state is rendered as [[karaten]].  In this state, the hand is not winnable as the number of available winning tiles is zero.  Such calls may be made by mistake, or intentionally invoked to cause players to defend.
 ==External links==
 {{jpwiki|立直}}
-*[https://ja.wikipedia.org/wiki/一発 一発]
+* [http://osamuko.com/yaku-hai-riichi/ Yaku, Hai!: Riichi (& Ippatsu & Daburu Riichi)]
-:Ippatsu in Japanese Wikipedia.
+: [http://osamuko.com/ Osamuko] article on riichi.
-*[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]]
+[[Category:Yaku]]
+[[Category:Game rules]]
 {{Navbox yaku}}