Ooyamaneko.net

The object of play is to form a complete hand. The ultimate object of the game is to accumulate the most points from the winning hands. It doesn’t matter how many hands each player has won; the accumulated score determines the winner.

A player’s turn begins when a tile is acquired and ends when a tile is discarded. During a normal set of turns all players have their turn once. A normal set of turns is interrupted if a tile is claimed for a chow, pung or kong, or if a concealed kong is declared.
A hand ends when a player has completed a hand and won, or if a drawn game occurs. During a round, all players are East in turn. A complete hanchan consists of two rounds: the East round and the South round.

A complete valid hand is composed of four groups and a pair, or seven different pairs, or the Thirteen Orphans yaku. A group may be a chow, a pung or a kong. Each group can be melded or concealed. In addition, a complete hand must have at least one yaku (scoring pattern). A player who is furiten is not allowed to win on a discard.

• A chow is three consecutive tiles of the same suit. A chow cannot be made with dragons or winds. 8-9-1 in the same suit is not a chow.
• A pung is composed of three identical tiles.
• A kong is composed of four identical tiles.
• A pair is composed of two identical tiles.

Players take their turns in order. East begins, and the turn order proceeds counter-clockwise. A player begins his turn by drawing or claiming a tile and ends his turn by discarding a tile. However, since East begins with fourteen tiles, he doesn’t draw a tile on his first turn.
Discards are placed in an orderly fashion, six tiles in a row, in front of each player and within the wall, so that it is clear who discarded which tiles and in which order. It is permissible to extend the third line of discards over six tiles.