From the cassette inlay:
THE SCENE: Alien spacecraft are using hyperspace drive to enter our universe through a black hole. Their intent is destruction.
YOUR MISSION: To uphold the defence of your universe as long as possible while inflicting the maximum damage on alien forces.
YOUR WEAPONS: Positive and Negative Ion Guns are deadly at any range but the ion stream is bent by the massive gravitational field of the Black Hole. The Neutron Blaster is equally deadly but has only limited range.
YOUR BATTLE: You are under constant attack from the alien force which pits fiendish offence craft against you in ever increasing intensity in deadlier and deadlier form.
How long can your fleet of ships survive?
How many enemy craft can you destroy?