Star Republic is about saving the world: satellites have detected an incoming asteroid headed to Earth; to say the least, its impact would have devastating effects on humanity. To make matters worse, the asteroid is swarming with an alien species none too keen on allowing you to destroy it. The alien's intention is to swarm upon the crippled Earth and harvest it for resources and human slaves; as such, they have set up defenses and a shield on the asteroid to protect its course from intervention.
Your ship, the Star Republic, is the only working prototype equipped to reach and effectively navigate the asteroid, Helios. Your mission: to destroy the shield generators protecting the asteroid, opening it up for a giant laser attack.