Your mission is not an easy and very dangerous. You will encounter the aliens are attacking the earth. They do it so quickly, that mankind first, and do not realize that aliens are evil and want us dead. But now it's too late, the only way to survive - is to go against them and start to destroy them. This is a very strange creatures, like colored balls, but it is very dangerous. Destroy them only in groups, if you get it wrong, they will get the immune system and make it harder to win!