Welcome to IJCAI 2023 Mahjong AI Competition. In this competition, you will develop a Mahjong AI that is able to compete with other agents and human players on Botzone, an online AI platform. The Mahjong Competition Rules (MCR) are based on Chinese Mahjong Competition Rules, also known as Chinese Official Mahjong. For learning MCR and debugging purposes, you are provided with a sample game-playing agent and a sample judge program used during the competition. The winner and the rankings will be determined after two rounds of competitions.

Mahjong is a four-player imperfect information game that originated in China over 3000 years ago. In 1998, the General Administration of Sport of China formalized Chinese Mahjong Competition Rules, the rules upon which this competition is based. In addition to game-playing strategies, luck is required to win a round of Mahjong, and exactly this uncertainty factor brought tremendous fun and challenges to Mahjong. Unlike other Asian mahjong variants, such as Japanese Riichi Mahjong, Chinese Official Mahjong encourages more aggressive game-playing strategies, thus it is more entertaining and attractive for both contestants and game watchers.

In Chinese Official Mahjong, players need to continuously analyze holding tiles, calculate possible winning hands, and pick a discarding tile for each turn. To make substantial progress in this competition, competitors may benefit from combining different AI methods, such as planning, game theory, heuristic search, Monte Carlo Tree Search, opponent modeling, machine learning, etc. Indeed, successfully integrating different kinds of methods remains one of the great challenges of AI nowadays. Best of luck with all your efforts and endeavors in this competition!

Pseudocode of the tournament


  • Competition Registration
  • Conference Registration
    • The participants who advance to the finals will need to register for IJCAI 2023 if they can give a presentation on site.
    • Each person belongs to at most one team.
  • Click here to view the competition group page.

Get Started

  • Click here to see how to use Botzone to join IJCAI 2023 Mahjong AI Competition.
  • Download sample program and submit to create your first Mahjong bot on Botzone!
  • Learn about basic rules of Mahjong and detailed input/output format of bots through our wiki page.
  • Frequently asked questions

Tips to be stronger


  • Registration Deadline: May 20th, 2023 (GMT+8)
  • Round 0 (Simulation Round): ~ May 20th, 2023 (GMT+8)
    • Simulation contests are planned every week, for participants to get familiar with the platform, game rules, and contest rules
    • Scores in Round 0 will not be counted
  • Round 1 (Tournament Round): May 21th, 2023 (GMT+8)
    • Swiss-system tournament and Duplicate Format will be used
    • Top 16 of the Round 1 will proceed to Round 2
    • The pesudo code of contest system is above.
    • Result of Round 1 will be announced on May 28th, 2023 (GMT+8)
  • Round 2 (Final Round): July 2rd, 2023 (GMT+8)
    • Swiss-system tournament and Duplicate Format
    • Final Round consists of two stages.
      • Stage 1: 256 rounds of Swiss-system with the same rules as the Tournament Round. 16 teams are divided into 4 groups by rankings in each round, and each group plays 24 games (full combinations of seating position)
      • Stage 2: Top 4 from Round 2 Stage 1 will fight for the championship. There are 512 rounds of Swiss-system with each round consisting of 24 games.
    • Final results will be announced on IJCAI 2023 session
    • Participants can not modify their bots between Stage 1 and 2.
  • Note: Click here to learn about the Duplicate Format rules.

Results Of Tournament Round

Top 16 in Tournament Round are listed here, with the exception of duplication and copycats.

Rank Team Account Score
14Return of the kinghumanfy658.01

Results of Final Round - Stage One

Top 16 in Stage One of Final Round are listed here.

Rank Team Account Score
15Return of the kinghumanfy586.98

Results of Final Round - Stage Two

Top 4 in Stage Two of Final Round are listed here.

Rank Team Account Score
1 麻将有风险输钱需谨慎 测功能的号 1361.0020


Wenxin Li
Professor in Peking University
Xiaotie Deng
Professor in Peking University
Yaodong Yang
Assistant Professor in Peking University
Guochuan Zhang
Professor in Zhejiang University
Yang Gao
Professor in Nanjing University
Haifeng Zhang
Research Fellow in University College London
Wenlong Li
General Secretary of Mahjong International League
Yutian Chen
Staff Research Scientist in Google DeepMind
LanZhou Zheng
CTO & Co-Founder of WEIZHIYU (Beijing) Technology co., LTd.
Haobo Fu
Principal Researcher in Tencent AI Lab


Our prior work on Mahjong AI and the platform Botzone:

  • Zhou, Haoyu, et al. "Botzone: an online multi-agent competitive platform for AI education." Proceedings of the 23rd Annual ACM Conference on Innovation and Technology in Computer Science Education. 2018.
  • Zhou, Haoyu, et al. "Botzone: a competitive and interactive platform for game ai education." Proceedings of the ACM Turing 50th Celebration Conference-China. 2017.
  • Zhang, Haifeng, et al. "Botzone: A game playing system for artificial intelligence education." Proceedings of the International Conference on Frontiers in Education: Computer Science and Computer Engineering (FECS). The Steering Committee of The World Congress in Computer Science, Computer Engineering and Applied Computing (WorldComp), 2012.
  • Li, Wenxin, et al. "Teaching AI Algorithms with Games Including Mahjong and FightTheLandlord on the Botzone Online Platform." Proceedings of the ACM Conference on Global Computing Education. 2019.



AI Lab, Institute of Network and Energy-Efficient Computing, School of Computer Science, Peking University, is led by Professor Wenxin Li, AI Lab is dedicated to artificial intelligence in games, as well as computer education, biometric recognition and related fields.
WEIZHIYU (Beijing) Technology Co., Ltd. is a company focusing on artificial intelligence and application of games. With advanced game AI technology and leading industrial share, WEIZHIYU has long-term cooperation with many academic institutes, including Tsinghua University, Peking University, Chinese Academy of Science and Beijing Information Science & Technology University, for cutting-edge artificial intelligence research. The company has a technical team with over 30 people and the core members graduate from famous universities like Tsinghua University and Peking University.

Technical support

MIL (Mahjong International League) is a global Mahjong organization conducted by the International Mind Sports Association, including formal Mahjong associations from more than 50 countries and regions of five continents. MIL initiates the duplicate format for the Mahjong competitions, which decrease the lucky factors effectively among the traditional Mahjong games. It is an important innovation to show a fair game and sublimate Mahjong from a game for fun to a real mind sport. By inheriting the idea of mind sports, MIL standardizes Mahjong as a competitive sport to bring Mahjong into mind sports games or even the Olympic Games.

Past Competitions

Competition Prizes
Rank Prize
Champion $5,000
Runner-up $3,000
3rd - 4th place $1,000
5th - 16th place Delicate gifts

The rules we adopt in this competition is Mahjong Competition Rules.

Click here to learn about detailed input/output protocol of Mahjong bots.
View source code of Mahjong judge program and the FanCalculator library for Mahjong scoring rule.
  • Click here to see how to use Botzone to join IJCAI 2023 Mahjong AI Competition. 2023-03-11

    IJCAI 2023 Mahjong AI Competition will be held as part of IJCAI 2023 in Macao, China, August 19th-25th, 2023. 2023-03-11

    Join the Wechat Group of Botzone. 2023-03-11

    Follow our Wechat Official Account for more information. 2023-03-11