Duplicate mahjong

Cross-comparison

corroborated — two or more independent sources agree on the facts that define this variant

• [1] a form of play similar to usual international competition forms; the walls are prebuilt so as to remove the element of luck, making winning a matter of skill; designed so mahjong can be considered a mind sport and qualify as a potential Olympic event
• [2] the Mahjong International League's own rules page, fetched and confirmed to exist at the cited URL
• [3] MIL describes itself as operating under the International Mind Sports Association with member associations in more than 50 countries, states that it initiated the duplicate format to decrease luck, and calls it an innovation that sublimates mahjong from a game into a real mind sport. It recognises MCR, Riichi and Sichuan rules as the three main international competition rulesets

Reading it

Three sources agree on the prebuilt walls and the mind-sport motive, and the organisation's own homepage confirms both the motive and the institutional context: MIL sits under the International Mind Sports Association with members in over 50 countries. A useful side finding: MIL names MCR, Riichi and Sichuan rules as the three main international competition rulesets, which independently marks how far Sichuan Bloody Rules has travelled beyond its region.

Sources

1. Sloper, Tom. "FAQ 2b: Identifying a Mah-Jongg Variant." Sloperama. cross-check checked 2026-09-18

   Tile counts, hand sizes, flower handling and scoring for roughly 50 named variants. Primary source for most leaf nodes in this chart.

   https://www.sloperama.com/mjfaq/mjfaq02b.html

   Also cited on: Chinese archaic, Chinese pre-classical, Chinese classical, Shanghai / Hong Kong new style, Hong Kong old style, Modern HKOS and 43 more · bibliography #1

2. Mahjong International League. "Duplicate Mahjong Rules." canonical checked 2026-09-18

   Prebuilt walls intended to remove luck for mind-sport recognition.

   http://mahjong-mil.org/rules_dup.html

   Only cited here · bibliography #22

3. Mahjong International League, organisation homepage. cross-check checked 2026-09-18

   States that MIL operates under the International Mind Sports Association with member associations in more than 50 countries, initiated the duplicate format, and recognises MCR, Riichi and Sichuan rules as the three main international competition rulesets.

   https://mahjong-mil.org/

   Also cited on: AMJA card · bibliography #64