Toutenkou
Toutenkou 「東天紅」 is a special 3-player mahjong variation mainly popular in Kanto region. Currently available in Tenhou computer matches (beta test).
Disclaimer: This page only introduces rules used in Tenhou. Details are not consistent, and variation exists in other platforms.
Rule Introduction
Only uses 
of manzu tiles, while all of pinzu, souzu and honor tiles are used (including red fives 
). 112 tiles in total.
are gari 「ガリ」 (similar to nukidora). 20 rinshan tiles in total.
A valid winning hand must include at least one of any regular yakus (identical to regular riichi mahjong yakus). A hand cannot win with only special yakus.
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 Yakus
Notes: All of the followings are bonuses. A hand cannot be claimed with only those following yakus.
(1 pt) Oya 「親」: Add one point when winning as dealer.
(1 pt) Menzen 「門前」: Add one point when the winning hand is concealed.
(1 pt) Honba 「本場」: Add one point for each honba.
(1 pt) Gari 「ガリ」: Add one point for each nukidora (). For it is also a red dora, so it actually worths 2 points.
(2 pts) Base point / Banban 「バンバン」: Add two points for each winning hand for no reason.
(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」 [note 1] : Add four points for each collected set of gari (four identical tiles of gari). Can be stacked with gari.
(8 pts) Ron 「ロン」: Add eight points when winning by other's dealing-in.
(10 / 20 pts) Crow / Karasu 「カラス」: Winning a hand without drawing any gari tiles. Add ten points when winning hand is opened, while 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 part is a bit weird. When indicator is
, dora is 
; when indicator is , dora is ; however when indicator is 
, none of the tiles is dora. [note 2] - Gari tiles can be used in hand, and also can be discarded, but can only get Gari's point when it is claimed as a nukidora.
- Set is still acquirable with some gari tiles used in hand. They're not required to be all claimed as nukidora.
- Riichi values 1 point. Riichi bet is also 1 point.
- A single round ends when there's no tile left before dora indicators.
- Noten penalty of ryuukyoku is 20 points.
- Gari can be claimed even in last turn.
- Rinshan Kaihou is available with rinshan tiles drawn from Gari.
- Crow / Karasu requires no any gari tiles both existing in hand, in discards and used as nukidoras.
- Yakuman yakus cannot stack with other regular non-yakuman yakus as usual, though they can still stack with toutenkou-specified special yakus. Each yakuman yaku values 20 points.
References
Notes:
External Links
- Toutenkou in Japanese Wikipedia
- Rule description of Tenhou's Toutenkou: http://blog.tenhou.net/article/186578700.html