Basic Setup
Four people sit around a square table, and dump all of the Mahjong tiles into the middle. The tiles are turned face down (so that you cannot see any numbered tiles) and "washed" or shuffled by mixing. Each player then builds a 34-tile "wall," grabbing any of the tiles in front of them and stacking them (face down) two high, placing 17 stacks next to one another to form a long line. Each person pushes his row of stacks forward, forming a square on the table.
Whoever is chosen as dealer rolls the dice. The number of the dice is the number of stacks from the end of the dealer&'s wall that the tiles will be drawn from. Starting with the dealer, each person takes two stacks (four tiles) from that point, performing this three times counter-clockwise until everyone has 12 tiles. Again beginning with the dealer, each player takes a tile (two tiles for the dealer, one tile for everyone else) to bring three players&' total tiles up to 13, and the dealers to 14.
Tile System
You can think of each tile as a playing card, with a number and suit printed on its front side. There are four suits in Mahjong: bamboo, circles, characters and winds/dragons. Each tile has a number and suit on it (for example, 3 of bamboo), except for winds and dragons, which are akin to face cards (higher value) but without a number. Instead, there are four types of winds and three types of dragons: East, North, South and West winds, and red, white and green dragon. If you have a Mahjong set from an English-speaking country, these names and numbers are most likely printed on the tile itself, for your reference.
Hands
Like many card games, Mahjong is a turn-based game, with each player picking up a tile and deciding what to keep and what to discard (face up) into the middle of the table. The goal is to, through drawing your own winning tile or picking it up from someone&'s discard, form a winning hand, which can be any variant of the following: four sets of three of a kind (number, not suit) of any suit, plus a pair; four sets of three-tile consecutive sets (i.e. 1-2-3 or 7-8-9) and a pair; or a slight variant on one of the two.
Scoring
The purpose of Mahjong is to get the highest winning hand before anyone else, and the scoring system is based on the contents of your hand. You can use poker chips or any type of chits as the basis for your system, assigning each chit a value of some multiple of two. A "regular" hand, such as the 3 of a kind or consecutive type, is worth two "points." The inclusion of any three of a kind involving a wind or dragon adds two points per set, and 4 of a kind of winds or dragons quadruples the value.
The score multiplier depends on how a player acquires her winning tile. If she picked it up herself during one of her pulls from a blank "wall," then the score is automatically doubled. Pulling it from a discard, however, does not multiply the score.