TICTACTOE

level 0 -- the Computer is totally dumb.
level 1 -- Computer is smarter (original version).
level 2 -- You MAY win (only when you start).
level 3 -- Computer NEVER lose.

To play Tictactoe, noughts, and crosses, or X-and-Os, two players mark three-by-three grids with Xs or Os, then switch roles. Three consecutive horizontal, vertical, or diagonal marks from the same player are considered the winner.

Gameplay

The strategy of playing Ultimate tictactoe is far more complicated than that of most other tictactoe variants. To put it simply, this is because of the game's intricate branching system. Even though each move must be made on a local board, the global board must be considered in numerous ways:

• The location of the opponent's next move is determined by the moves made on the local board. Due to the opponent being transported to a different local board and not being able to respond instantly, moves that would be judged terrible in standard tictactoe may become viable. As a result, players are compelled to look at the entire game board rather than just their piece of the puzzle.
• It is more difficult to visualize the game's future branches than it is to play tictactoe on a single board. Predicting future movements is substantially more difficult because each move is dependent on the previous one. Positions on the board will no longer be interchangeable in the future, with each move resulting in drastically different probable future positions. Due to the difficulty of visualizing the game tree, many potential paths may go unnoticed.
• Winning the game: The global board is never directly influenced by the rules of ultimate tictactoe. Acts taken by local boards are the only ones that have any bearing on it. Rather than attempting to win a game at the local level, each move is being made in an attempt to win the overall game. When a local victory cannot be leveraged to gain control of the global board, it may be smarter to give up a local victory to your opponent in exchange for control of a more significant local victory. As a result, it becomes more difficult for humans to assess the relative relevance and significance of movements, making it more difficult to play well.

Implementations of computer code

A brute force approach cannot be used to solve the most difficult version of tictactoe, which is impossible to solve using depth-first search. To play this game, more innovative computer implementations are required.

A common AI strategy known as minimax can be utilized to play ultimate tictactoe but has a hard time with this game. This is due to the lack of a simple heuristic evaluation function in ultimate tictactoe, despite its very basic principles. Minimax needs this function since it determines how good a particular position is. Even though basic evaluation functions for ultimate tictactoe can be built by taking into consideration the number of local triumphs, these generally disregard positional advantage, which is much more difficult to measure. Few computer opponents can consistently outplay humans due to the lack of an efficient evaluation function in most conventional computer implementations.

Artificial intelligence algorithms that don't require evaluation functions like Monte Carlo tree-search can easily play this game. As a result of the Monte Carlo tree search's use of random game simulations rather than positional evaluations, it is capable of accurately assessing a present position's value. Minimax solutions are outperformed by computer implementations based on these methods, which can easily defeat human opponents.

Also Read: Tictactoe