Ooyamaneko.net

Claiming the last discarded tile for a melded kong is done by clearly calling “kong” or “kan”, placing the tile face-up along with the three matching tiles from the hand. After revealing a new kan dora, the player takes a replacement tile from the dead wall and continues his turn as if he’d drawn a tile from the wall.
The dead wall always comprises 14 tiles, so after a kong the dead wall is replenished with the last tile of the wall.

Claiming the last discarded tile for a pung is done by clearly calling “pung” or “pon” and placing the tile face-up along with the two matching tiles from the hand.

A tile can only be claimed for a chow from the player on the left. Claiming the last discarded tile for a chow is done by clearly calling “chow” or “chi”, placing the tile face-up along with the two tiles from the hand that complete the set.

Tiles in melded sets can not be rearranged to form other sets, and they cannot be discarded.
After calling a tile, the relevant tiles from the hand are immediately exposed. It is allowed to make the discard before the claimed tile is taken. If the claimed tile is not taken within the next two opponents’ turns, i.e. before another two discards has been made, the player has a dead hand.



Melded sets are placed to the right of the players tiles in clear view for all players. Claimed tiles are rotated to indicate which player made the discard. If the tile was discarded by the player sitting on the left, the claimed tile is put on the left side of the set. If the tile was discarded by the player sitting in front, the claimed tile is put in the middle of the set. If the tile was discarded by the player sitting on the right, the claimed tile is put on the right side of the set. A claimed kong has one rotated tile. A kong made by extending an open pung has two rotated tiles: the extending tile is placed by the previously rotated tile.
   

A player who feeds the third dragon pung/kong to an opponent with two melded dragon pungs/kongs or the fourth wind pung/kong to an opponent with three melded pungs/ kongs of winds must pay the full value of the hand in case Big Three Dragons or Big Four Winds are made on a self-draw (the two remaining opponents pay nothing). In case another opponent feeds the Big Three Dragons or Big Four Winds, he shares the payment equally with the player who fed the third dragon pung/kong or the fourth wind pung/kong.

A melded pung may be extended to a melded kong in a player’s turn after the player has taken a tile from the wall or a replacement tile, i.e. not in a turn where a tile was claimed for chow or pung. The player must call “kong” or “kan” clearly, place the fourth tile by the rotated tile of the pung, allow 3 seconds for mahjong declarations and then reveal a kan dora and take a replacement tile. The dead wall is replenished with the last tile of the wall.

A concealed kong may be declared in a player’s turn after the player has taken a tile from the wall or a replacement tile, i.e. not in a turn where a tile was claimed for chow or pung. The player must call “kong” or “kan” clearly, reveal the four tiles of the kong, then turn the two middle tiles face-down, reveal a kan dora and take a replacement tile. The dead wall is replenished with the last tile of the wall.
A player still has a concealed hand after declaring a concealed kong, if the player has no open sets.
A concealed kong cannot be robbed, except to win on Thirteen Orphans.
Note that four identical tiles only make up a kong, if a concealed kong is declared.

If no-one wins on the discard after the fourth kong, the hand ends in abortive draw, except in the case where it’s the same player who has all four kongs, in which case playing continues, but no further kongs may be declared. Under no circumstance can a fifth kong be made.

A player who can form a valid mahjong hand with at least one yaku with the last discard, can win by clearly declaring ron or mahjong, unless he is furiten.

A player who can form a valid mahjong hand with at least one yaku with a tile just drawn from the wall or the dead wall, can win by clearly declaring tsumo or mahjong. The player should keep the winning tile apart from the rest of the hand, so that it is clear to all players which was the winning tile. A player who is furiten can still win on self-draw.

A player with a concealed waiting hand can declare riichi by clearly saying riichi, rotating the discarded tile sideways and paying 1000 points to the table by placing a stick by the discards. If an opponent claims the rotated discard for winning, the riichi declaration is invalid and the 1000 points are returned to the riichi declarer. If an opponent claims the rotated tile for a melded set, rotate your next discarded tile.
A player is not allowed to declare riichi if there are less than four tiles left in the wall.
The 1000 points goes back to the riichi declarer if he wins. If another is the winner of the current hand, he collects the 1000 points, and in case of a drawn game the riichi bet stays on the table to be claimed by the next player to win a hand.
A player who declared riichi can no longer change his hand. However, he may declare a concealed kong if a tile is drawn that matches a concealed pung, if this does not change the waiting pattern and if the three tiles to be konged can only be interpreted as a pung in the original riichi hand. (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).
It is permissible for a player who is furiten to declare riichi. A player who after declaring riichi, chooses not to win on a discard that completes his hand, becomes furiten. A player who is furiten can still win on self-draw.
Riichi is a yaku. A player who wins in the first set of turns after the riichi declaration (including the player’s next draw) can claim an additional yaku for ippatsu. The ippatsu chance is lost if the set of turns is broken by claims for kong, pung or chow, including concealed kongs.
A player who wins after declaring riichi, reveals the tiles underneath the dora indicator and any kan dora indicators. These tiles indicate ura dora which can be claimed only by players who declared riichi.