On looking at the packaging for this 1986 (1986!) game, you could easily be forgiven for thinking it's some sort of reasonable-looking Defender clone. You'd be mistaken though, as it is in fact the worst Defender clone it's been my misfortune to stumble across.
It features shamefully garish graphics, the most laughable attempt at simulating Defender's inertial movement system I've ever seen, totally ridiculous gameplay mechanics (like the homing missiles which are completely unavoidable unless you take your craft to the very bottom of the screen, whereupon they harmlessly and inexplicably self-destruct) and, and...
Look, just don't buy it, okay?