Challenge the computer in three different AI modes.
Just select a difficulty setting at the top and begin by selecting your first move (by clicking on a tile).
The 'easy' AI chooses its moves at random.
In medium the AI will 'look ahead' and play either a winning move (if it exists), block the players winning move or move randomly (in that order).
The hard ('ultron') setting is unbeatable. Since tic-tac-toe is a solved game with a small and finite number of possible moves, setting the computer to hard (i.e. play with perfect strategy) means that you can only tie or lose on this setting.
This game was written with vanilla javascript, HTML and CSS.