Enter your 3 character initial, select the target aliens. Before time runs out, you need to pick all target aliens, and reach the needed points for each level. You have 3 types of aliens which will bring to you different points.
The claw is moving in a clockwise direction, and you can press space button or mouse click to change the direction. When you will place the claw under the alien, use the shadow to make it easy, and press the red button to pick up the aliens.