Sky-Defense, the first game put out by Quasar Animations, is loosely based on the arcade hit Defender. However, there are no humans to rescue, and you can't reverse direction (the latter being similiar to Avenger). Otherwise, it is similiar in the way you fly over terrain, and the aliens you must shoot. It should be mentioned that Quasar Animations later came out with a much closer clone of Defender, called Guardian, in 1983.
Title: Sky-Defense
Author: ???
Publisher: Quasar Animations
Released: May 1982
Requires: Color Computer 1,2,3, 16K RAM, cassette or disk, joystick.