RecursiveTicTacToe is TicTacToe with the possibility to set the level of recursion: 0 is the simple TicTacToe, 1 is the Ultimate TicTacToe, 2 and 3 are even more "recursive" games.
https://adebiasi.github.io/RecursiveTicTacToe/
1 level of recursion (Ultimate TicTacToe)
2 level of recursion