X si 0 is a free puzzle game developed by Mihai Masala for Android devices. It is a classic game of tic-tac-toe that can be played in two modes, either against a friend or against an AI. The game is easy to play and understand, making it suitable for all ages.

In the first gameplay mode, you can play against a friend by taking turns to mark the spaces on the board with X or O. The game ends when one player successfully places three marks in a row, either horizontally, vertically, or diagonally.

In the second gameplay mode, you can play against an AI, which has two difficulty levels - easy and hard. The easy level is suitable for beginners, while the hard level is more challenging and suitable for experienced players.

Overall, X si 0 is a simple and fun game that is perfect for passing the time or playing with friends. It is a great way to relive childhood memories of playing tic-tac-toe and is a must-try for puzzle game enthusiasts.