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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, but only the discarder pays for any counters.

After declaration of a fourth kong the game continues, but no further kongs may be declared during this hand. 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’s hand is tenpai or waiting if the hand needs only one more tile to complete a winning hand. A player is still considered tenpai if all his waiting tiles are visible among the discards and declared sets. A player is not considered tenpai if he is waiting only for a tile of which he already has 4. A player is not considered tenpai if his hand has been declared a dead hand.

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. In case of multiple winners, the 1000 points are collected by the winner first in order after the discarder. 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.