That's not actually Go. That's a game literally called Reversi. Also known as Othello.
https://en.wikipedia.org/wiki/Reversi
This power is also pretty similar to another classic children's game. Onigokko, also known as Kagome Kagome. It's basically "tag", but those who get tagged also become "oni" and hunt down the others. I think this is the best fit for what Imu's doing. There's even a song. And it'd be interesting for Imu to have a song of their own to oppose Nika's Drums of Liberation.
https://bujinkansantamonica.blogspot.com/2012/10/onigokko-lets-pretend-we-are-demons.html
https://en.wikipedia.org/wiki/Kagome_Kagome
Also, Imu summoning various weapons, like the dagger and the gun? That COULD be a reference to the board game Clue, also known as Cluedo. With the weapons Imu summons all being based on the possible murder weapons. So, Imu could also have access to a lead pipe, or some rope. (It was Imu, on Elbaph, with the revolver!)
https://en.wikipedia.org/wiki/Cluedo
The book? That could be a classic Monster Manual from Dungeons and Dragons, or something.
https://en.wikipedia.org/wiki/Monster_Manual
https://en.wikipedia.org/wiki/Dungeons_&_Dragons
If this is all right, that seems to hint that Imu's powers are "game" based. Just like how Luffy's powers are "imagination" or "cartoon" based. Which probably means Imu has one of the God Fruits. Which one is debatable. But, one of the other three.
So, Imu actually could have Go powers, too. We just haven't seen Imu use those, yet. But, Imu likely also has other "board game" based powers. Like Chess, or Monopoly, or Mouse Trap, even.