These little monsters are daring you: catch me if you can! Well, that's what you'll show them. Shoot the right items into the right direction and eliminate the little monsters. When there are no more monsters left, you move on to the next level. When you hit the brown energy balls (with a lightning bolt inside), you'll increase your firepower.
Use WASD, the arrow keys or just the mouse to move and press the left mouse button to shoot. If you hold the left mouse button for two seconds, you can fire an extra powerful shot: this can be useful if you want to break down a wall for instance.