THE BIRTH OF ZELOS COULD MEAN THE DEATH OF ZILLIONS
In a remote quadrant of the universe there was hatched a hideous creature. His proud parents, Ma & Pa Deltoid, named their only son Zelos, which in alien lingo means "one mean son of a gun."
As Zelos grew into an adult space monster, his appetite turned ravenous, his temper became ruthless, and his name proved an understatement. It didn't take long for Zelos to leave the nest and go out on his own, devouring everything in sight, including three galaxies, four hundred planets, two trillion life forms and a side order of stars.
Then your innocent galaxy appeared on Zelos's menu, and he chowed on an entree of roast Gradius, with the planit Latis for dessert. Now, the only chance these civilizations have of escaping from his digestive tract lies with you and your starfighting partner.
But your odds look pretty grim, for Zelos is full of floating armada terror zones, which are cities that have become a part of Zelos after being eaten. Each of these zones is loaded with tremendous firepower and unbelievable destructive suprises. You'll also find that Zelos's heart and soul are positioned safely behind his traitor fleet.
That means you'll have to devastate the six Terror Zones and pblast away their grotesque mayor before reaching Zelos's main artery and putting an end to his eating binge.
--From the NES Life Force instruction manual.