Yaku
Yaku 「役」 are specific hand patterns or conditions needed in order to score a hand, analogous to poker hands. Yaku are worth specific han values, and various yaku can be combined into one hand. Basic mahjong knowledge involves learning the yaku, but it is not expected of new players to know all of them. Most importantly, every hand must include at least one yaku in order to count as a winning hand.
Han
Each yaku is assigned a han value. Whenever a player wins, their hand's yaku are tallied up, and they score points based on the total amount of han. If a hand has multiple possible interpretations, the highest possible hand is always scored.
Open vs closed
A hand is considered open if it makes a tile call from another player's discard. These include chii, pon, and open kan. Otherwise, it is closed.
Some yaku can only be scored closed; they are invalidated when the hand opens. Other yaku reduce in value if part of an open hand. The rest of the yaku score the same regardless if a hand is open or closed.
Nomi
Nomi 「ノミ」 is a hand that contains only one yaku and no dora. For example, riichi nomi 「リーチノミ」 means "riichi only". The term is mostly used for low value yaku, like tanyao and pinfu. It is acceptable to use it for higher value yaku, like chinitsu, but this is rarely done.
Yaku types
The different yaku focus on different types of patterns and circumstances. They are mostly derived from the tiles within one's hand. A number of yaku also involve the state of one's hand pertaining to the timing of certain tile draws and discards.
Discard based
These two are yaku because the hand is tenpai during specific discard timings. As a result, these two yaku can never be won via drawing a tile.
- Winning with a tile used for an added kan by another player.
- Winning off of the last possible discarded tile for the hand.
Discretionary
- This is the only yaku by which players have the option to declare or not. Otherwise, hands may possibly win without it, if it remains closed with other valid yaku.
- This is essentially riichi, but with the added luck of the hand being tenpai upon the initial tile deal, or the opening hand.
Draw based
These are yaku by virtue of the drawn tile. Thus, these three can never be won directly from other players.
- Winning with the last tile draw.
- Drawing the winning tile with a closed hand.
- Drawing a winning tile after a kan call.
Honor based
Honor based tiles depends on the use of honor tile groups. Each of these cases also are mixed with the numbered tiles.
- Honor tiles with one suit.
- Honor tiles with terminals.
- Specific collection of all three dragon types.
- No honors or (terminal) are used.
- Specific collection of any dragon, seat wind, or round wind tiles.
Riichi dependent
Ippatsu cannot occur without a call for riichi.
- Winning on or before the next tile draw after riichi.
Sequential
These yaku require sequential tile groups.
- By definition, this yaku uses two-identical sequences.
- A complete string of 1-9 tiles, arranged into sequences of: 123, 456, and 789.
- Every tile group must be a sequence (among other conditions).
- By definition, this yaku uses two-identical sequences two times.
- By definition, this yaku uses three identically numbered sequences across the three suits.
Terminal based
These yaku revolve around terminals, or complete lack thereof.
- Every tile group with an honor or terminal.
- Only honor and terminal groups.
- Every tile group with a terminal.
- No terminals (or honors) are used.
Triplet based
These yaku require at least one triplet in order to be valid.
- Three closed triplets.
- Requires three quads, which are considered as triplets plus one extra.
- Needs three identically numbered triplets across the three suits.
- Triplets of dragon tiles.
- Every tile group is a triplet.
- Counted when the hand contains a triplet of a valid honor tile, namely: any dragon triplet, appropriate seat wind, or the current round wind.
Suit based
- All tiles are the same suit or honor tiles.
- All tiles are the same suit.
Yakuman
Yakuman is a special class of yaku, by which the pattern itself is awarded the maximum point limit for a single hand pattern. These are among the most difficult to complete; and players may treat them as special.
Combining yaku
Different yaku may be implemented into a single hand. By doing so, the values applied to the different yaku also combine. In short, they stack. This aspect of the game is key towards developing larger scoring hands. With dora, the stacking effect becomes even greater.
Optional yaku
A list of optional yaku exist due to the game's complexity, which can further explore possible tile combinations and patterns. Regardless, the yaku list noted above is the more commonly accepted list.
See Also
External links
- Yaku in Japanese Wikipedia
- Wikipedia listing
- Yaku frequency among Tenhou.net players (Japanese)
- Lists all the yaku occurrences in Tenhou.net by percentages and by room
- Pointing out which yaku to learn first