Many alien ships are attacking the expanses of the earth. They are not very friendly, so you have to destroy them all to one. The only difficulty in this whole matter is that the number of missiles you have is strictly limited, so you will have to act to the limit of your ability to destroy the rest of the ships with the remains of those already knocked out. Be very careful and do not forget that each successfully completed mission gives you extra points that you can use for the necessary improvements. Good luck!