The gun itself isn't too interesting (from a "strange Star Wars" point-of-view), but that's understandable once you know that Kusan was already selling the toy before Star Wars was released. In 1977, though, the Astro Zapper got a new and improved box, one that would catch the attention of Star Wars fans. Let's take a look at the back of that box, shall we?
That sure looks like a stormtrooper to me. And watch out, he's surrounded by his rainbow force field!
This guy with the pink helmet is a bit less blatant, but it seems like Kusan's version of Darth Vader. Notice the lightsaber and also the detail on the body, similar to the control box on Vader's chest.
On the top and bottom of the package is a spaceship, two people, and an Astro Zapper logo different from the one shown on the front. This one really reminds me of the "pyramid" Star Wars logo.
Here's a close-up of the two people, one armed with the Astro Zapper toy. There doesn't seem to be any Star Wars inspiration here.
The left and right sides of the box have the "X-wing", too. It also has a funny looking alien/ monster wielding a gun.
Looking at the sides within the box's window, you can see a spaceman shooting a stormtrooper wannabe.
This gun is white but it also a black one, which I've seen come with a yellow background for the box's interior (see it at danefield.com, which states that that version is from 1979).
Kusan also made the classic Sonic Fazer gun toy, but that's a post for another time. I have to buy one, first!