Star Stormer

"Go to the conquest of space, by trying to save the planet Terra II from the Xull invaders...In this game you are one of the best space navigators of your planet: Terra II, a new human colony. 

It has been now 200 years that the first humans have arrived here...there has been until now no problems with the neighbor races of this planetary system, but a few months ago, the planet Xull had plans to expand themselves: The government of Terra II has decided a general mobilization and you have been chosen to protect the space around Terra II: your mission order: DO NOT LET ANYTHING APPROACH FROM TERRA II. Good Luck!"

(Source: https://www.macintoshrepository.org/4283-star-stormer)