When KFourInLine loads, you can select the difficulty or start a two player game. If you like, you can also pick your color and select which color starts the game.
Each player is represented by a color (for example yellow or white for player one and red for player two). The goal of the game is to get four connected pieces of your color into any row, column or diagonal. The players move in turns. Each turn the player can place one of his or her pieces into any of the seven columns where each piece will fall to the lowest possible free place i.e. it will fall down until it reaches the ground level or another piece.
After one player's move is done the second player can make his or her input. This is repeated until the game is over, which is when one of the players has four pieces in a row, column or diagonal or no more moves are possible because the board is filled.
A player who first manages to get four pieces in a row, column or diagonal wins the game. If no more moves can be made but no player has won, the game ends drawn.