Gonin mahjong

Gonin mahjong 「五人麻雀」 (lit. "five-person mahjong", sometimes abbreviated to goma 「五麻」) refers to a number of five-player variants of Japanese mahjong. At this point, there is no established ruleset governing this mode of game play.

The easiest method to accommodate five players is by playing regular four-player mahjong, and alternate which player sits out each hanchan. With minor changes, it's possible to rotate players after each hand, allowing for shorter wait times between each player's turn to play. While it's very rare, it's possible to play with five players at the same time if bigger changes are introduced, eliminating the need for one person to wait on the side.

Alternating players each hand

When determining initial seats, shuffle one white dragon together with one of each wind tile face down. Each player takes one tile, and sits at the seat whose seat wind corresponds to the tile they took. The player who took the white dragon is the first to sit out a hand.

The article at echigo-kmj.com recommends that the person who was the dealer (east seat) gives up their seat to the waiting player at the end of each hand, and the dealer role rotates as usual, with the new player's seat becoming North. This way, each wind round is 5 hands long. It is recommended not to play renchans, to ensure that every player plays the same amount of hands, and there is no risk of waiting on the side for a long time.

An alternative method that minimizes winning and losing streaks (recommended at majyan-item.com), is to switch out the player that won the hand. Instead of rotating the dealer role, the new player becomes the dealer. In case of an exhaustive draw, the seated players remain, but the dealer role rotates to the right.

Waiting players can take the opportunity to study the other players' play styles from behind, or take a bathroom break.

To engage the waiting player more, it is also possible to introduce a betting system, where the waiting player takes a look at each player's hand before the first discard and writes down who they think is most likely to win the hand, earning points if they guess right and losing points if they're wrong.

Five players simultaneously

Common changes

These changes from the four-player rules are most commonly recommended for playing with five players at the same time:

• The length of a wind round increases to 5 hands (not counting renchans, if those are used).
• Four flower tiles are added to function as the seat wind of the player to the left of the dealer. (Seat winds: East → South → West → North → flowers.) The difference between the individual flowers is ignored. This increases the total amount of tiles from 136 to 140, so each player builds a wall of 14 tiles long.
• The dead wall is reduced to two tiles only: the dora indicator and the uradora. This is to increase the amount of tiles each player draws before ryuukyoku as close to a 4-player game as possible, without eliminating dora. Calling kan does not add an extra dora, and the player calling kan draws from the live wall instead.

Scoring

There are two main methods for scoring in case of a tsumo:

• The dealer role is ignored, dividing the score into 4 in all cases. (In this case, there is little point in having a renchan if the East seat player wins.)
• The same payments as the four-player game are used when a non-dealer wins, effectively giving them a 25% bonus if they win by tsumo. The dealer's score is divided by 4, so e.g. a dealer scoring mangan (12000 points) receives 3000 points from each player. (If the payments from four-player games were used for dealer tsumos, dealers would have a 33% tsumo bonus on top of their 50% dealer bonus.)

Other possible changes

• If flowers are used as seat wind tiles, some yakuman may be changed or added in response to the added tiles.

• Kokushi Musou (13 Orphans) can be changed to require one of each of the 14 terminals and honor tiles (including a flower tile), instead of requiring a pair.
• Suushiihou (Four Winds) can be adapted into a new Five Winds yaku (Japanese: Uushiihou 「五喜和」), which is a Suushiihou where the remaining two or three non-wind tiles are all flower tiles. It should count as multiple yakuman, if those are allowed.
• The original Suushiihou and Kokushi Musou with a pair can be retained, but they are easier to make if flower tiles are allowed to be used. As a consequence, their value may be reduced to a mangan.

If the above yaku changes are not used, flower tiles should probably not be allowed in Suushiihou and Kokushi Musou.

• Chii calls may be allowed for the second player to the left of you. This is called a "large chii". When two players call chii, the regular ("small") chii gets priority.
• A fifth copy of each tile may be added, as well as a new tile call: "kin" is like kan but with 5 tiles. If two players declare pon on the same tile, the closest player in turn order gets it (a type of atamahane).
• A fourth suit may be added, if the necessary tiles are available. 4-suit versions of sanshoku doujun (three-colored straight) and sanshoku doukou (three-colored triplets) may also be added.