You have to form color lines using boxes that change color every time you select a line. The boxes change from red to yellow, to green and then back to red. There are 3 different game modes: Normal (get as much points as you can before your turns run out), Endless (play against your patience and get as much points as you can) or Board (try to set all the squares in the same color in as few turns as you can). To change the color of a specific square you need to click with the mouse on 1 of the two buttons outside the board that are aligned with the square. This will make the whole line of squares to change their color. You'll get points for each line you make. If you manage to make more than one line at the same time, you earn special bonuses and medals.