It would be cool if when player wins on a certain board, that board gets marked O or X, and the game is finished when there are 3 boards, winned by same player, in a row? I hope that it's understandable enough.
You mean like Tic Tac Toe within a bigger Tic Tac Toe? That was the original idea by VSauce, but I changed it to # of games won because it felt more intuitive when playing