[bradwood]

How about the ancient Chinese game of "go", next? Not convinced that can easily be solved at all.

[tromp]

Go is considered close to being solved on a 7x7 board [1]. The grand challenge would be solving 9x9 Go, the standard beginner board size.

Note that professional players are far from mastering 9x9, and regularly play 9x9 tournaments.

Solving the full 19x19 game is utterly out of the question.

[1] https://forums.online-go.com/t/katago-attempts-to-solve-7x7/...

[mafuy]

There was a recent push for 9x9. It's not solved but it is believed to be near perfect play.

https://katagobooks.org/9x9highlights.html

[mikpanko]

Among popular board games, Go is more computationally complex than chess, so the latter would probably be solved first.