"For hundreds of years humans have searched for an answer to the eternal question: Are we alone in the universe?
Get armed, kill the enemy. Follow the story as you explore the levels and call for help. If you keep improving, your 3 types of tanks or Valkyrie and Fighter spaceships can keep you a step ahead of the enemy. Can you save the capital cities of earth? Defeat is not an option, humanity could be annihilated!
Space Force HOMEWORLD is a game in which the player combats a large number of alien forces, by shooting at them while dodging their fire. Both on land and in space it is a classic struggle filled with droves of aliens and weapon powerups."
Source: The Developer Website.