The game mission is to defend the Earth from the space invasion, you are Earth latest hope, so do your best and defend the road that leads to your base and to Earth. There are waves of machines rushing to your base so build many types of towers to defend the road that leads to it. Your success is based on your money, lives and the way you think and act. You start the game with only 150 dollars and for each enemy you destroy you will receive an amount of money. This amount depends on how big the opponent is. You only have 5 lives and your base wont handle more than 5 enemies. If this happens you will lose and you will have to start over. Also, try to overthink your attack plan and manage to earn money so that you are able to improve your towers. You can do this by upgrading the range, fire rate and damage. Become the best player online and from this National Defense:Space Assault games and save the Earth during these 8 intense levels. And you can try the mobile version for free to unlock full version of the game. As always have a blast online on vitalitygames and good luck with the game. Have fun!