Years from now the people of Earth colonize another planet called Cognita, found near Rigel Kentaurius (Alpha Centauri A). It is the only place besides Earth where the human race can survive and grow.
That is, however, until another planet is discovered. 68 light years from Earth and not far from Aldebaran, one of the Taurus constellation's stars, the "third Earth" awaits. Not long after the discovery, a fleet of Sundivers, mind controlled ships the size of large cities, begin the trek to the new planet. But on the way there, they are intercepted by an alien race.
While controlling one of the many Sundivers, build an army with enough fire power to defend the rest of the fleet from the new enemy, and continue the mission to colonize the "third Earth".
Starmageddon was initially designed as a space sim similar to Wing Commander. However, late in development, the developers were told that space sims has no future and the game was redesigned as a Homeworld clone.
Ironically, the sequel which started out as a Homeworld clone was later modified into a space sim.