UNCHAIN Inc. has released a new style of Mahjong game ‘THIRD Mahjong’ equipped with a unique system “THIRD” that allows viewers to intervene in the game in real time on April 21, 2026, for PC browsers. This latest version of an intervention-type platform for streamers is based on the concept of “from spectators to participants,” allowing viewers to influence the flow of the stream in real time.

“Intervention-type” Mahjong created by Mahjong enthusiasts – Hand and discard tiles temporarily hidden

This project was developed by a special project team of Mahjong enthusiasts within UNCHAIN. Born from the desire to make Mahjong streaming more casual and enjoyable for viewers, its main feature is audience intervention through THIRD. Key intervention actions include “hand hiding,” which temporarily hides the player’s hand; “discard hiding,” which hides all players’ discard tiles; and a disruptive character called “Cindy.”

Due to the “false calls” caused by hidden tiles being a deduction item, players are required to have good memory skills. Since all players must declare their discards when playing, it is said to serve as memory training even for serious Mahjong players. Currently, only a single-player mode is available, but multiplayer implementation is planned, and battles between streamers and viewers rooting for their favorite players are also anticipated.

Platform “THIRD” promoting “from spectator to participant”

THIRD is UNCHAIN’s proprietary system that evolves the traditional “view-only” live streaming into a “game for streaming” where viewers can directly intervene in the game in real time. Streamers play THIRD-compatible games in their usual streaming environment, while viewers can purchase items to carry out intervention actions such as “increasing enemies (interference),” “restoring players’ health (support),” and “sending special items.”

Stepping beyond traditional “support,” the concept aims to provide a new enthusiasm that creates a cooperative or competitive relationship between the streamer and listeners, crafting the stream together. The latest information is communicated on THIRD official X and official Discord, with registration channels available for both streamers and developers.

Future Developments: Ongoing “Game No. 1 Deciding Match” with a total prize of 10 million yen

UNCHAIN is currently hosting a developer contest “Game No. 1 Deciding Match” targeting innovative game works utilizing THIRD. With a total prize of 10 million yen, the entry conditions require the implementation of THIRD link features in works (new or existing) by July 31, 2026, with evaluation criteria based on the innovation of viewer intervention experiences, excitement in streaming, and uniqueness of implementation. The results announcement is scheduled for September 2026.

As for ‘THIRD Mahjong,’ future updates including online multiplayer are anticipated, which could significantly change the context of Mahjong streaming once a competition environment with interventions is established. As a rising platform in the streaming game space, it seems that the movement involving both developers and streamers will continue.

Thoughts and Outlook

The “type of game experience where viewers can ruin/help the stream” has been explored in the context of overseas Twitch extensions for a long time, but the incorporation of this into Japan’s ultra-standard title of Mahjong is what makes this work interesting. The rule design where false calls incur penalties excellently retains the essence of Mahjong as a memory game. As the STMAG editorial department, we are focusing on how far THIRD can involve developers with the multiplayer implementation and 10 million yen contest, and whether it can become a regular tool for streamers.

Source: PR TIMES