What is riichi compared with other mahjong in Mahjong (Riichi)?

Verdict

Riichi is one of several mahjong rule families and is clearly distinct from the others, though all share the same core: build four sets and a pair from tiles; Mahjong Competition Rules (MCR) is the other major competitive rule set. Its current text is the World Mahjong Organization's 2014 English...

Why people argue about this

People often assume that Riichi is just another name for Mahjong itself, forgetting it's a distinct competitive variant with its own rules set by MCR. In reality, they're conflating Riichi, which adds bidding and betting elements to the game, with the broader concept of Mahjong as a pastime or even an abstract strategy game.

Send this to your friend — argument over.

6. Variants & House Rules

Riichi Compared with Other Mahjong

Riichi is one of several mahjong rule families and is clearly distinct from the others, though all share the same core: build four sets and a pair from tiles
Mahjong Competition Rules (MCR) is the other major competitive rule set. Its current text is the World Mahjong Organization's 2014 English edition, which supersedes the widely circulated 2006 "Green Book" that EMA still names as the reference for its MERS ranking tournaments — so a European MCR event may run under the older text. EMA runs MCR tournaments under its own MERS regulations, meaning the same association supervises play under both rule sets
Japanese professional leagues each carry their own rule variations, and riichi rules exist in many versions differing in etiquette, scoring, and which variants are enabled

Common Options Not Used by EMA

Red fives — widely used in Japan, where each red five gives one han. Not used in EMA riichi (1.3)
Flower, season and joker tiles are set aside; they belong to other mahjong variants (1.3)

What Changed in 2025

A delayed call for a triplet or quad no longer takes priority over a preceding call for a sequence (3.3.1)
Riichi may now be declared with at least one tile left in the wall (3.3.10)
Yaku are classified by their closed han value and lose value in open hands (4.2)
An Etiquette chapter was added and the Errors and Penalties chapter expanded to list every error

Tournament Conventions

Sessions may be time-limited; a hand is treated as beginning immediately after the previous one ends (3.1, 7.4)
Organisers may supply an all-last sheet for tracking scores during the final hand (3.6)
A chombo (major penalty) during the last hands of a timed session counts as one hand, to protect the schedule (3.4.6)

6. Variants & House Rules

Riichi Compared with Other Mahjong

Riichi is one of several mahjong rule families and is clearly distinct from the others, though all share the same core: build four sets and a pair from tiles

Mahjong Competition Rules (MCR) is the other major competitive rule set. Its current text is the World Mahjong Organization's 2014 English edition, which supersedes the widely circulated 2006 "Green Book" that EMA still names as the reference for its MERS ranking tournaments — so a European MCR event may run under the older text. EMA runs MCR tournaments under its own MERS regulations, meaning the same association supervises play under both rule sets

Japanese professional leagues each carry their own rule variations, and riichi rules exist in many versions differing in etiquette, scoring, and which variants are enabled

Common Options Not Used by EMA

Red fives — widely used in Japan, where each red five gives one han. Not used in EMA riichi (1.3)

Flower, season and joker tiles are set aside; they belong to other mahjong variants (1.3)

What Changed in 2025

A delayed call for a triplet or quad no longer takes priority over a preceding call for a sequence (3.3.1)

Riichi may now be declared with at least one tile left in the wall (3.3.10)

Yaku are classified by their closed han value and lose value in open hands (4.2)

An Etiquette chapter was added and the Errors and Penalties chapter expanded to list every error

Tournament Conventions

Sessions may be time-limited; a hand is treated as beginning immediately after the previous one ends (3.1, 7.4)

Organisers may supply an all-last sheet for tracking scores during the final hand (3.6)

A chombo (major penalty) during the last hands of a timed session counts as one hand, to protect the schedule (3.4.6)

Riichi Compared with Other Mahjong