You can win if the values of the squares are equal horizontally, vertically or diagonally
You can play in a horizontal or vertical position of the screen

You and your friend can play on the same device
In case of victory or draw, click on the replay icon at the bottom of the screen until a new game starts
You can press the replay icon at the bottom of the screen until a new game starts at any time while playing

Or.....
You can play online for up to levels
Escalate levels from very easy to very difficult
The level increases with each game you win
The level decreases with each game you lose
Every time you open the program you will find your level as you left it the last game
In case of a win or a draw, wait until a new game starts