How SUO plays

Jan 9, 2024 | 3 minutes read
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As mentioned above, the mahjong AI called SUO, which is used in the mahjong app R Mahjong, was tested in a game against the mahjong AI Akochan. To give the reader an opportunity to appreciate the strength and style of SUO’s play, it was originally intended to post recordings of SUO’s games against Akochan.

However, Akocan’s license does not seem to allow this. Here’s what the license specifically allows (translation into English):

・This program can be used freely for private research and consideration.

・As long as it is for non-commercial purposes, the output of this program (tile records, evaluation values of mahjong situations) may be reprinted, reproduced, published, and broadcast, with a clear statement that this program was used.

・Other uses (such as publication by individual business owners or commercial organizations) are only possible with the permission of the creator.

Therefore, we decided to post a number of recordings of SUO vs SUO games. R Mahjong uses the game recording format from the mjai project [1], but to read such recordings you must install R Mahjong or another application capable of displaying this format. I used the html game recording format from the same mjai project. Thus, these game records can be read directly in the browser without installing additional software.1

Since simply watching SUO play can bring true pleasure, we have created the 麻雀AI channel on YouTube2 in which we will post videos of these games played.3, 4

When recording a game, Training Mode is enabled, which is a powerful way to improve your mahjong game. In this mode, you see the hands of your opponents and tips from the AI. This way you can see in detail what is happening and how the AI will evaluate a particular tile for discarding.


1 Of course it doesn’t look as nice as in the R Mahjong application. At the same time, it is quite possible to improve the appearance replays recorded in html format, so from the point of view of aesthetics, replays in this format will not be anything inferior to replays in any other representation.

2 麻雀AI and tokachan channels were also created on and

3 To appreciate the beauty of the SUO game, we recommend watching at a reduced speed.

4 I know that I am not objective. I like the way SUO plays. Yes, I treat SUO almost like a person. Apparently, many other creators of artificial intelligence for mahjong have similar feelings. I know there are stronger mahjong players (including AI). At the same time, given the limitations of mobile platforms, it is difficult to create more powerful AI mahjong without using huge neural networks. There are other restrictions besides technical ones. However, I hope that SUO will play mahjong even stronger in the future.