Disclaimer: This page only introduces rules used in Tenhou. Details are not consistent, and variation exists in other platforms.
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.
Ron takes points from only one opponent (with 8 more extra points than tsumo).
Tsumo takes points from two opponents.
Notes: Both 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.
(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.
- 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.
- 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.
- Set is also called Storm / Arashi 「アラシ」 in some platform.
- Toutenkou in Japanese Wikipedia
- Rule description of Tenhou's Toutenkou: http://blog.tenhou.net/article/186578700.html