Mahjong Engines
Tencent · Riichi, Chinese Official

LuckyJ 绝艺

Tencent’s mahjong AI holds the highest stable rank an AI has posted on Tenhou, and was the first AI to beat top professionals at Chinese Official (Guobiao) mahjong.

Announcement ↗
Built by
Tencent 13
Rules
Japanese riichi, Chinese Official 12
Approach
Self-play RL with regret minimization (ACH) 2
Strength
Tenhou 10 dan, stable rank 10.68 12
Access
Research, no public release

Who built it

LuckyJ (Chinese name 绝艺) is Tencent’s board and card game AI 3. Tencent announced its mahjong result on 11 July 2023 12. Coverage credits the core technique to Tencent AI Lab 3.

Rules

LuckyJ plays Japanese riichi on Tenhou and Chinese Official mahjong (Guobiao, the national standard rules) 12.

How it works

Tencent says LuckyJ uses ACH (Actor-Critic Hedge), a policy optimization algorithm that combines reinforcement learning with regret minimization in self-play. It learns from scratch and converges to a strong mixed strategy 23. For play under hidden information, it adds a search method built on optimistic value estimation, which lets deep reinforcement learning be combined with imperfect-information search 2.

ACH was published at ICLR 2022 by Tencent researchers 4. Instead of maximizing discounted returns, it minimizes a weighted cumulative counterfactual regret, approximated by a neural network, with Hedge producing the self-play policy 4. The paper tested it on 1-on-1 Mahjong, a two-player variant, where the agent beat a human champion 4. The paper does not cover the four-player game LuckyJ plays on Tenhou.

Strength

LuckyJ reached 10 dan on Tenhou with a stable rank of 10.68 12. It got there in 1,321 games 1. Tencent says this is the best stable rank among registered players in that room with over 1,000 games 2. For comparison, TechNode puts top human stable ranks at about 7.4 1, and Suphx reported 8.74 in 2019.

At Guobiao, LuckyJ beat six professional players in an offline invitational, which Tencent describes as the first time a mahjong AI beat top Guobiao professionals 12.

How to access it

We found no public code, model or playable service for LuckyJ. The ACH paper 4 is the published part of the method.

Sources

  1. TechNode, “Tencent’s mahjong AI sets new gaming record on international mahjong platform” (12 July 2023)
  2. IT之家, report on LuckyJ reaching Tenhou 10 dan (July 2023, Chinese)
  3. 量子位 QbitAI, report on LuckyJ (July 2023, Chinese)
  4. Fu et al., “Actor-Critic Policy Optimization in a Large-Scale Imperfect-Information Game”, ICLR 2022

Facts checked against these sources on 24 October 2026.