Alien invasion of earth

Published: Mar. 18,2013 Tags: ET   Physics   Skill   Puzzle

Intro: Alien planet is inhabited by a group of strange alien small ball, ball one day scientists discovered there may be they need resources on the earth, so alien sent alien ball to invade earth, began to look for resources they need, what is their resource? Gold oil? Or something else? Now let's go to help an alien balls for resources they need.

Hold the left mouse button drag cloned ball, mouse the left key click remove balls.