Game details:

A large asteroid was heading to Earth which would exterminate all life. Luckily aliens came in and mined this asteroid for resources which caused the asteroid to explode into smaller pieces. The alien forces are picking up some scraps, but unfortunately the mothership left. They are leaving most of the smaller asteroids alone, which would still kill millions of people on Earth. It is your job to make sure all asteroids will be destroyed so no lives are lost on Earth. But unfortunately the aliens are not very friendly...