Invincible game??? Exactly!
The project is built with HTML, CSS, Javascript. This tic-tac-toe game applies a minimax algorithm to AI players and no one player can beat it.
You can try it at https://tanhongit.github.io/JavaScript-Tic-Tac-Toe-Project/
Read more: Rails application: Tic Tac Toe with multiple modes : https://github.com/TanHongIT/rails-tic-tac-toe-project
