Toutenkou

Toutenkou 「東天紅」 is a 3-player mahjong variant mainly popular in the Kanto region. It is currently available in Tenhou computer matches (beta test).

Disclaimer: This page only introduces the rules used in Tenhou. Details are not consistent, and variation exists in other platforms.

Rule Introduction

There are 112 tiles, 28 types in total. All pinzu, souzu, and honors are used; only of manzu are used. There is one red five of each suit.

are gari 「ガリ」; gari tiles function identically to nukidora in sanma:

• They can be called and set aside to count as 1 dora. After the call, one tile is drawn from the dead wall; winning with the tile scores rinshan.
• They can be used in the hand or discarded, but won't count as dora.

There are 20 rinshan tiles in total.

Scoring

A valid winning hand must include at least one regular yaku; it cannot win with just special yaku. The list of "regular yaku" is identical to the standard riichi mahjong yaku.

Instead of calculating with fu and han, the score is only counted with points.

Ron takes points from only one opponent (with 8 more extra points than tsumo).

Tsumo takes points from two opponents.

Special Yaku

Every valid winning hand obtains an extra 2 points by default (listed as base point / banban 「バンバン」). This is similar to the base 2 han used in the riichi mahjong scoring formula (the "+2" in base points = fu * 2^(han + 2)).

All of the following yaku are bonuses. Like dora, a hand cannot be won with only these yaku:

(1 pt) Oya 「親」: Add one point when winning as the dealer.

(1 pt) Menzen 「門前」: Add one point when winning with a closed hand.

(1 pt) Honba 「本場」: Add one point for each honba.

(1 pt) Gari 「ガリ」: Add one point for each tile called for gari and set aside like nukidora (). is also a red dora, so it is worth 2 points.

(2 pts) Minkan 「明槓」: Add two points for each opened kan.

(4 pts) Ankan 「暗槓」: Add four points for each concealed kan.

(4 pts) Set 「セット」  : Add four points for having all four copies of a gari tile. A hand can score this yaku multiple times, and it can be stacked with gari. This does not require the tiles to actually be called for gari, e.g., a closed triplet of 5m + a called 5m will still count towards this yaku.

(8 pts) Ron 「ロン」: Add eight points when winning by another player's discard.

(10 / 20 pts) Crow / Karasu 「カラス」: Win a hand without drawing any gari tiles. Worth ten points when winning hand is opened, or twenty points when concealed.

(20 pts) All Gari 「全ガリ」: Add twenty points when collecting all gari tiles. Can be stacked with gari.

Notes

• Dora for manzu:
  • A 1m indicator points to 9m; a 9m indicator points to 1m.
  • When 5m is the indicator, no tile is considered dora.
• Riichi is worth 1 point. The riichi bet is also 1 point.
• A single hand ends when there is no tile left before the dora indicators.
• The noten penalty at ryuukyoku is 20 points.
• Gari can be claimed even in the last turn.
• Yakuman yaku cannot stack with other regular non-yakuman yaku as usual, though they can still stack with toutenkou-specified special yakus. Each yakuman is worth 20 points.

References

Notes:

External Links

• 東天紅_(麻雀)

Toutenkou in Japanese Wikipedia

• Rule description of Tenhou's Toutenkou: http://blog.tenhou.net/article/186578700.html