You have to push the balls into the pots of the same color. You earn more points if you shoot less times. In level 1 there's just a green ball and a green boat; in level 2 are added a blue ball and a blue boat; in level 3, a red ball and a red boat. In this way it goes more complex until the 20th level, where the game ends.
If you put the mouse on the ball an arrow will be visible, move the mouse to define power and direction of the shot and click to shoot.