American mahjong is a variation on the classic Chinese game and was standardized by the National Mah Jongg League of New York in 1937. It is played by four players and most closely resembles the card game gin rummy; instead of cards, players build sets of tiles.
Mahjong has many different types of tile pieces. There are three sets: bamboos, dots and characters. Each set contains four sets of tiles numbered from one to nine. There are four each of four "winds" tiles: east, south, west and north. There are four tiles each of three "dragon" tiles: red, green and white. There are eight "flowers" tiles, which are pairs of tiles numbered one through four. There are eight jokers.
All players roll the dice to determine seating order. The highest roll goes into the east position, the next highest is south, who sits to the right of east. West sits to the right of south, and north to the right of west. This is the order of play: east clockwise to north.
All of the tiles are mixed and placed face-down. Each player draws 38 tiles and stacks them so that he has 19-tile-long rows, two tiles high. The rows are connected at the ends to create a square.
The east player breaks the wall to start the deal. She throws the dice and counts from the right end of the wall she built, to the left. At the number indicated by the dice, she splits open the wall slightly. She then picks up the first two sets of tiles (four tiles) at the left of the break. The other players follow clockwise.
Players do this twice more, so that everyone has 12 tiles. The east player takes the top tile from the next left stack; the south participant takes the one below it; the west participant takes the next top left tile; the north player takes the one below it; and the east player takes the next top left tile.
In American mahjong, a "Charleston" is used. Each player swaps three tiles with the player to his left, then three with the player across the table, then three with the player to his right. If all players agree to it, another swap takes place, in reverse order of the first one.
Players sitting across the table from each other can exchange one, two or three tiles if they both want to. If one wants to exchange a lesser number than the other, the lesser number of tiles are swapped.
Jokers can't be passed at any time.
As with gin rummy, players try to make sets and get rid of all of their cards. Sets are two, three, four, five and six of a kind. Jokers are wild and are used to create any set except pairs.
East goes first by discarding a tile face-up. After that, players pick up a tile and discard a tile. A player may pick up a discarded tile to make a set. He must, however, put down his set and declare it (threes, fives and so forth). Play resumes with the player to his right.
If two players vie for a discard, the tile first goes to a player who is picking it up to declare a win; otherwise, it goes to the player whose turn comes soonest.
If a joker is used in a set, any player holding a tile that matches the number for which the joker substitutes may exchange the pieces. A pair can't be built from a discard unless it is to end the game. The game ends when one player gets rid of all of his tiles.