Ooyamaneko.net

Several yaku require the hand to be closed.
When a closed hand is won on a discard, the last group or pair is considered to be melded, but the hand is still closed.

Yaku are cumulative unless specified otherwise, so several yaku may be combined in the same hand.
Yakuman yaku are not cumulative.

Riichi — Riichi — [The hand must be closed]
Closed waiting hand declared at 1,000 points stake.

The player must declare riichi by clearly saying "riichi", rotating the discarded tile sideways and paying 1,000 points to the table by placing a stick by the discards.

If an opponent claims the rotated discard to win, the riichi declaration is voided and the 1,000 points are returned to the riichi declarer. If an opponent claims the rotated tile to make a group, the riichi declarer must rotate his next discard.
A player is not allowed to declare riichi if there are less than four tiles left in the wall.

A player who declared riichi can no longer change his hand. However, he may declare a concealed kong if he draws a tile matching a concealed pung, if this does not change the waiting pattern and if the three tiles can only be interpreted as a pung in the original riichi hand. (E.g. in case of three consecutive pungs in the same suit, no kong may be declared, since the tiles can be interpreted as three identical chows).

A player can declare riichi even if he's furiten.

Ippatsu — Ippatsu — [The hand must be closed]
A player who declares riichi will be rewarded for Ippatsu if he wins during the next uninterrupted set of rounds, including if he wins by self-draw on his next draw.
Calls for chow, pung or kong, including concealed kong declarations, interrupt the round, making Ippatsu invalid. Riichi declarations do not interrupt the round.

Double Riichi — Daburu riichi — [The hand must be closed]
A player who declares riichi on his first discard, during the very first un-interrupted set of turns, will be rewarded for Double Riichi.
Calls for chow, pung or kong, including concealed kong declarations, interrupt the round, making later Double Riichi invalid. Riichi declarations do not interrupt the round.

Fully Concealed Hand — Menzen tsumo — [The hand must be closed]
Winning on a self-draw on a closed hand.

Pinfu — Pinfu — [The hand must be closed]
The pinfu yaku is awarded for winning on a closed pinfu hand.
A pinfu hand is a hand worth no minipoints beside the 20 minipoints for winning and the 10 minipoints for winning on a discard on a closed hand. The 2 minipoints for winning by self-draw are omitted in order to qualify as a pinfu hand and thus to score the pinfu yaku.

Technically, a pinfu hand has four chows and a pair that is neither dragons, nor seat wind, nor prevailing wind; the winning tile completing a chow with a two-sided wait.

Pure Double Chow — Iipeikō — [The hand must be closed]
Closed hand with two completely identical chows, i.e. the same values in the same suit.

All Simples — Tan'yao
Hand with no terminals and honours. The hand can be open or closed.

Yakuhai — Yakuhai
Pung or kong of dragons, the player’s seat wind or the prevailing wind.
Multiple yakuhai combines.
If the player’s seat wind is the same as the prevailing wind, a pung or kong of this wind scores yakuhai twice.

Robbing a Kong — Chankan
Winning on a tile that an opponent adds to a melded pung in order to make a kong. Since the kong is not declared successfully, no kan dora is revealed.
Robbing a Kong is scored as a win on a discard.
Robbing a Kong also applies when winning on Thirteen Orphans on a tile used by an opponent for making a concealed kong. A concealed kong can only be robbed in the case of Thirteen Orphans.

After a Kong — Rinshan kaihō
Winning on a replacement tile after declaring a kong.
Counts as self-draw; the two minipoints for winning on self-draw are awarded.

Last Tile Draw — Haitei
Winning on self-draw on the last tile of the live wall.
If the last tile of the wall is a replacement tile drawn after a kong, only After a Kong will be scored. I.e. you cannot score Last Tile Draw and After a Kong together.

Last Tile Claim — Hōtei
Winning by claiming the discard after the last tile of the wall.

Seven Pairs — Chiitoitsu — [The hand must be closed]
Closed hand with seven different pairs. Having two identical pairs invalidates this yaku.
Seven Pairs always scores exactly 25 minipoints; extra minipoints for e.g. a pair of dragons are not awarded.

Pure Straight — Ikkitsukan / Ittsū — [Worth only one han if the hand is open]
Hand with three consecutive chows in the same suit.

Mixed Triple Chow — Sanshoku dōjun — [Worth only one han if the hand is open]
Hand with three chows of the same numerical sequence, one in each of the three suits.

Outside Hand — Chanta — [Worth only one han if the hand is open]
All groups contain terminals or honours, and the pair is made of terminals or honours.
The hand must contain at least one chow.

All Pungs — Toitoi
Hand with four pungs / kongs and a pair.

Triple Pung — Sanshoku dōkō
Hand with three pungs / kongs of the same number, one in each suit.

Three Concealed Pungs — San'ankō
Hand with three concealed pungs / kongs.
Note that the entire hand is not required to be closed.

Three Kongs — Sankantsu
Hand with three kongs.

All Terminals and Honours — Honrōtō
Hand containing only terminals and honours.
Add two han for All Pungs or Seven Pairs.
Does not combine with Outside Hand.

Little Three Dragons — Shōsangen
Hand with two pungs / kongs of dragons and a pair of dragons.
Add the two han for the individual pungs / kongs of dragons.

Twice Pure Double Chows — Ryanpeikō — [The hand must be closed]
Closed hand with four chows forming two distinct Pure Double Chows.
Does not combine with Pure Double Chow.

Half Flush — Hon'itsu — [Worth only two han if the hand is open]
Hand with tiles from only one of the three suits, in combination with honours.

Terminals in All Groups — Junchan — [Worth only two han if the hand is open]
All groups contain terminals, and the pair is made of terminals.
The hand must contain at least one chow.
Does not combine with Outside Hand.

Blessing of Man — Renhō — [The hand must be closed]
Winning on a discard in the very first un-interrupted set of turns, before the player has had his first turn.
Calls for chow, pung or kong, including concealed kong declarations, interrupt the round, making later Blessing of Man invalid. Riichi declarations do not interrupt the round.
Blessing of Man is not cumulative with other yaku and dora.

Full Flush — Chin'itsu — [Worth only five han if the hand is open]
Hand composed entirely of tiles from only one of the three suits, without any honours.
Does not combine with Half Flush.

Blessing of Heaven — Tenhō — [The hand must be closed]
East player winning on his initial dealt tiles.
Not valid if the player declares a concealed kong.

Blessing of Earth — Chihō — [The hand must be closed]
Winning on self-draw in the very first un-interrupted set of turns.
Calls for chow, pung or kong, including concealed kong declarations, interrupt the round, making later Blessing of Earth invalid. Riichi declarations do not interrupt the round.

Thirteen Orphans — Kokushi musō — [The hand must be closed]
Closed hand with one of each of the thirteen different terminal and honour tiles, plus one extra terminal or honour tile. The hand can be completed on any tile; it does not need to be waiting on thirteen different tiles.

As a special case, it's possible to rob a concealed kong to win on Thirteen Orphans.

Nine Gates — Chūren pōto — [The hand must be closed]
Closed hand consisting of the tiles 1112345678999 in the same suit, plus any one extra tile in the same suit. The hand can be completed on any tile; it does not need to be waiting on nine different tiles.

Four Concealed Pungs — Sūankō
Hand having four concealed pungs and/or kongs.
I.e. a closed hand with four concealed pungs, completed by self-draw or by claiming a tile to complete the pair.

Four Kongs — Sūkantsu
Hand with four kongs.

All Green — Ryūiisō
Hand composed entirely of green tiles. Green tiles are: Green dragon and 2, 3, 4, 6 and 8 of bamboo. The hand is not required to include the Green dragon.

All Terminals — Chinrōtō
Hand composed entirely of terminal tiles.

All Honours — Tsūiisō
Hand composed entirely of honour tiles.

Big Three Dragons — Daisangen
Hand with three pungs and/or kongs of dragons.
A player feeding the last pung or kong may be subject to liability payment.

Little Four Winds — Shōsūshi
Hand with three pungs and/or kongs of winds and a pair of winds.

Big Four Winds — Daisūshi
Hand with four pungs and/or kongs of winds.
A player feeding the last pung or kong may be subject to liability payment.