TORI uses rules largely based on the rules used by the WRC. Two sets of rules are in use for in-person play: one for casual gameplay, and one for tournament gameplay. The tournament rules are simply WRC rules, whereas the casual rules are the staff’s preferred mix of WRC, EMA and Tenhou rules.

For online play, Tenhou rules are used by nature of playing on Tenhou.

A list of terms can be found below.

Rule Casual Tournament Source (casual) Notes
Kuitan Ari WRC, Tenhou Open tanyao is allowed.
Atozuke Ari WRC, Tenhou The hand does not need to contain a yaku before the winning tile is claimed.
Starting 25,000 30,000 Tenhou Players start the game with this many points.
Goal 30,000 WRC, Tenhou At least one player must have at least this many points for the game to end normally (i.e. not reach an extra round).
Oka 0 WRC There is no bonus for being in first place.
Uma 15/5/-5/-15 WRC After dividing the scores by 1000, this is the amount to add for each player.
Akadora One of each (as available) Nashi WRC (mod), Tenhou Whether red fives are used. Red fives are worth one extra dora each.
Calling precedence Ron→first WRC Ron precedes all calls. If no ron, then the first call has precedence. If calls are done simultaneously, pon/kan have priority over chii.
Kuikae Nashi WRC, Tenhou Swap calling is not allowed. Swap calling is discarding the same tile that was called, or the opposite side of a ryanmen wait.
Minimum points to riichi 1000 N/A WRC (mod), Tenhou The minimum number of points to legally call riichi.
Enchousen Ari N/A Tenhou
If no player has reached the goal score, the game goes into the next round (West for a hanchan and South for a tonpuusen). Play continues until the end of the round is reached, or the dealer is in the lead and above the goal score if a renchan would normally occur, or a player has met the goal score and a renchan would not normally occur. Enchousen lasts for only one round.
Abortive draws Nashi WRC There are no abortive draws, including suucha riichi, suufon renda, suukaikan, kyuushuu kyuuhai, and sanchahou.
Tobi Ari Nashi WRC (mod), Tenhou
The game ends when a player has less than 0 points.
The game continues even if a player has less than 0 points.
Agariyame Ari Nashi Tenhou
A dealer in the lead who has met the goal at oorasu may choose to end the game immediately instead of continuing a renchan.
A dealer renchan cannot be terminated early.
Double ron Ari Atamahane Tenhou
When two players call ron on the same discard, both players receive payment.
Only the player closest to the discarder in turn order wins the hand and receives payment.
Triple ron Ari Atamahane EMA
When three players call ron on the same discard, all three players get paid.
The player closest to the discarder in turn order wins the hand.
Renchan Winning hand, dealer tenpai WRC, Tenhou The dealer keeps their dealership and a honba is added when they win a hand, when they are in tenpai at an exhaustive draw, or when there is an abortive draw (if applicable).
Noten riichi Nashi WRC, Tenhou Calling riichi without being in tenpai is not allowed and will be penalized with chombo at ryuukyoku.
Ryanhan shibari Nashi WRC, Tenhou Hands still only need a minimum of one han to win with five or more honba on the table.
Daiminkan, shouminkan kandora Immediately WRC When an open kan or added kan is called, the kandora is flipped immediately after the call.
Ankan kandora Immediately WRC, Tenhou When a closed kan is called, the kandora is flipped immediately after the call.
Furiten riichi Ari WRC, Tenhou Declaring riichi while in furiten is allowed.
Nagashi mangan Ari, winning hand, closed only Nashi WRC (mod)
Ari, winning hand, closed only
A nagashi mangan is treated as a winning hand at ryuukyoku. The hand must be closed (i.e. the player must not have claimed any tiles).
Nagashi mangan is not a win, nor is it treated specially at ryuukyoku.
Renhou Ari, mangan WRC A player declaring ron before their first draw is awarded a mangan or the value of the hand, whichever is greater. No tiles may have been called by any other player prior to the ron.
Kokushi ankan chankan Ari Nashi EMA A player may call ron on a closed kan if it completes a kokushi musou.
Daisharin Nashi WRC, Tenhou A closed hand comprised of pairs from 2-8 in one suit is not scored as yakuman by itself.
Ryuuiisou Hatsu not required WRC, Tenhou When going for ryuuiisou ("all green"), hatsu (green dragon) is not required in the hand.
Paarenchan Nashi WRC, Tenhou Hands won with 8 honba on the table are scored normally.
Open riichi Nashi WRC, Tenhou Players cannot reveal waits when calling riichi.
Kan on riichi Ari, doesn't change interpretation or waits WRC A kan may be called after calling riichi only if doing so does not change the waits or the interpretation of the hand.
Pinfu tsumo 20 fu WRC, Tenhou The 2 fu for tsumo are waived when pinfu tsumo is scored.
Chiitoi 2 han, 25 fu WRC, Tenhou The value of chiitoi is 2 han. The hand is always scored as 25 fu.
Double wind pair 4 fu 2 fu Tenhou The number of fu scored by a pair of winds that is both the round wind and the player's seat wind.
Rinshan tsumo 2 fu WRC, Tenhou The 2 fu for tsumo still applies when winning by rinshan.
Pao Daisangen, Daisuushi Daisangen, Daisuushi, Suukantsu Tenhou The discarder of a third dragon or fourth wind when another player has already visibly claimed the two or three other sets is liable to pay the value of the whole hand if the hand wins by tsumo, or half its value if won by ron. For tournament play, the discarder is also liable to pay when discarding a tile that is claimed as another player's fourth kan (suukantsu pao). No liability is incurred for discarding a tile that leads to a rinshan (rinshan pao).
Double yakuman Nashi WRC, Tenhou A single yakuman is never worth double its value. This includes daisuushi and the pure wait forms of kokushi musou and chuuren poutou.
Yakuman stacking Ari WRC, Tenhou If a hand is composed of multiple yakuman, the value of each yakuman is counted.
Kazoe yakuman Ari Nashi Tenhou
A hand worth 13+ han is scored as a yakuman.
A hand worth 13+ han is scored as a sanbaiman.
Kiriage mangan Nashi Ari Tenhou
A hand worth 3 han 60 fu or 4 han 30 fu is scored as a mangan.
A hand worth 3 han 60 fu or 4 han 30 fu is scored normally and not rounded to a mangan.
Pao bonus sticks Discarder WRC If a win involves pao, the bonus sticks are paid by the discarder.
Double/triple ron bonus sticks Atamahane N/A Tenhou
For multiple ron, the bonus sticks are given to the winner that is closest to the discarder in turn order.
Uma in case of tie Split/Divide WRC Multiple players with the same score at the end of the game will split the uma evenly between them.
Remaining riichi bets Lost WRC Any riichi bets left after the final hand are lost.


Other terms can be found in the Riichi Wiki.

European Mahjong Association
World Riichi Championship
WRC (mod)
World Riichi Championship, optional rules for casual play