Ultra Tic-Tac-Toe

Ultra tic-tac-toe rules

About the game

Ultra tic-tac-toe is a variant of the classic tic-tac-toe, where nine boards of the regular tic-tac-toe are arranged in a 3 X 3 grid. The goal of this variant is the same as regular tic-tac-toe, i.e. make three in a line within one of the smaller boards, in a row, or in a column, or one of the diagonals.

You win the game if you're the first one to do so.

You lose if your opponent achieves it first.

And the game is a draw if the board has no more empty cells.

Game rules

There are two players X and O who take alternate turns.

The game randomly chooses the first player (X). O is always the second player. Additionally, the game randomly chooses one of the nine smaller boards as the starting board, let's call it the "active" board.

The first player chooses any of the open cells in the "active" board. The relative position of their choice within that "active" board determines the next "active" board.

For example, if your opponent chose to play in the "Top Right" corner of the small board, then in your next turn, you have to play in one of the open cells of the small board in the "Top Right" corner of the 3 X 3 board-grid.

X

➜

X

There is one exception to this rule. If the next "active" board has no empty cells, then the entire grid of 81 X 81 cells becomes valid for the next player.

For example, if your opponent had played in the center cell of a small board, and the center board of the 3 X 3 board-grid is already full, then you would be allowed to choose your move from any of the empty cells in the entire 81 X 81 cell-grid.

O

O

X

X

X

O

X

X

O

X

O

X

O

X

O

X

O

O

X

➜

O

O

X

X

X

O

X

X

O

X

O

X

O

X

O

X

X

O

O

X

This continues until

  • Either one of the player wins by the regular tic-tac-toe's victory rules,
  • Or when there are no more empty cells.

Playing the game

The board will highlight the small board that you are allowed to play within, or all the cells if you can play in the entire 81 X 81 cell-grid.

The unavailable cells will still be visible, just a little faded.

Left-click any of the valid cells that are empty to make your play. Then the game will proceed to your opponent.

Tips & Tricks

These are based on my play style. Feel free to employ them or ignore them as per your own experiences and play style.

  1. This is a substantially different game than the regular tic-tac-toe, in terms of tactics and strategies. Just because a move was good in the regular game does not mean it is a good move here.
  2. It is generally a strong position when you have advantage in several small boards, i.e. two in a row / column / diagonal, and the third cell in that line is still empty.
    • This prevents your opponent from playing moves that lead to that small board.
    • At one point, they might end up in a situation where all moves lead to the boards where you have advantage.
    • Note that your opponent could try to do the same!
  3. Don't worry if your opponent is close to winning in one of the small boards.
    • You might be able to win on a different small board, before the game ever comes back to that small board.

This is a challenging game to master, and the higher levels of AI can certainly throw wrenches in your plan! Try to estimate what your opponent would want to play, and use that to force them into a loss. Don't shy away from trying out different strategies.

To learn more

I came across this variant of tic-tac-toe during college, and found it incredibly fun. There are even more variants of tic-tac-toe, and Wikipedia is a great source to learn about the regular version and its other variants.