This is a kind of solitary game, opposing a human player and a virtual opponent, the smarphone.

The game board has 16 cells, 4 lines and 4 columns. Each player owns 4 pawns: red for the human and black for the opponent.
At game beginning, the pawns are aligned on their base rows.

Aim of the game is tho place three pawns of your color aligned in diagonal, or four pawns aligned in vertical.

The human player moves first: select a red pawn touching it: its colour changes to blue. Then touch the destination cell, which must be empty, and just une step away from the starting position, in any direction. Or a red pawn may jump over a black one, provided that the destination cell is empty. If the move is valid, the selected pawn will be moved to the new selected position.

After each move of a red pawn, the move is up to black, and you have to wait for it. Once done, the move is up to you again, and so on.