The "University of Tokyo Naemura Lab" exhibited "PlayBranch" at Tokyo Game Show 2025 (hereinafter, TGS2025), which was held at Makuhari Messe starting on Thursday, September 25, 2025!
We interviewed University of Tokyo student Tasuku Tanaka, who belongs to the Naemura Lab and is one of the developers.
The "University of Tokyo Naemura Lab" at TGS2025!
The "University of Tokyo Naemura Lab," led by Professor Takeshi Naemura (@naemura), was attracting attention in the Game Academy Corner.
This was the first time the University of Tokyo had exhibited at TGS.
We went to see exactly what kind of exhibit they had!
The "PlayBranch" System for Taking Over Play From Let's Play Videos
Saiga NAK
"PlayBranch" is a system developed to allow viewers to take over gameplay while watching a Let's Play video and post it as a new Let's Play video.
Viewers can intervene in the Let's Play video that they were only passively watching. It's possible to beat the streamer's record, try a different branch, or start a new game from a board state constructed by a skilled player.
Furthermore, the inherited play can branch into a new Let's Play video, which can then be inherited by another viewer, allowing for a chain-like form of play.
Everyone has been annoyed or wanted to play a game themselves while watching a Let's Play video at least once, right?
We actually tried out "PlayBranch," which makes such wishes come true.
Saiga NAK
First, we chose a Let's Play video from which we wanted to inherit the game play.
This time, we chose the classic puzzle game "Tetris."
It's a strange sensation to be able to play from where the video left off...
We got a Game Over, but someone else will surely break the record!
It's fine even if you fail, as everyone is building it up together.
It was a fun, new kind of game play, whether inheriting it yourself or watching others' branches.
Interview with Tasuku Tanaka, University of Tokyo Student in the "PlayBranch" Development Team
(Following block quotes are translated from Japanese.)
― "PlayBranch" was very interesting! It's a system unlike anything before, isn't it?
Tanaka: For example, when a streamer makes a mistake in a Let's Play video and the viewer thinks, "I would do this," I wanted to create a system where the viewer can rewind the game and play from the point they chose.
That play can also be posted as a new Let's Play video and inherited by someone else again.
As everyone played it at TGS2025, the branches increasingly became like a parallel world.
In addition to "Tetris," we have made it possible to incorporate assets for anything implemented in Unity, such as racing games and "2048," by simply inserting them.
― Is the Naemura Lab specialized in games?
Tanaka: The lab itself deals with a wider field—the area of interaction, which looks at how human behavior changes when using computers.
Since I joined about two years ago, I've been allowed to pursue game research, which is what I wanted to do.
― Are there any game-related labs at the University of Tokyo?
Tanaka: For example, there are places that do research on creating game AI through AI learning, or gamification.
Among those, we are researching how to expand the ways games are played.
― You liked games to begin with, Tanaka.
Tanaka: I usually play games and also create them.
The first one I made was in my second year of high school, and it was a very simple one at the time.
After entering university, I continued to create games on my own and with multiple people.
― It seems your research and love for games are linked.
Tanaka: I believe this research is connected to my history of playing games.
My favorite game is "Outer Wilds," a space exploration game.
I also like high-difficulty games such as "SEKIRO: SHADOWS DIE TWICE," and I played them extensively.
― This is the University of Tokyo's first time exhibiting at TGS. Who was the initiator?
Tanaka: I requested to bring "PlayBranch" out, and I was given the very valuable experience of exhibiting at TGS.
I was happy to have many people visit and give us positive feedback.
― Do you have a message for high school students or new students starting in April?
Tanaka: I want to tell them that you can make what you love into research.
I think there are many labs doing research on things other than games, so please find a place where you can do what you want and enjoy your research while working hard.
"PlayBranch" is a system created by Japan's top university to make games even more enjoyable.
We will continue to watch the "Naemura Lab," which is pursuing various research, with keen interest!