A set of Star Wars knock-off figures was released in 1978 as a part of Arco Industries' Play Kid line of toys (which were similar in the size and look of Playmobile toys). This subset was called Spacewar (sometimes referred to as Space War), which was made up of C-3PO, Chewbacca, Darth Vader, R2-D2, a stormtrooper, and a generic space guy with a lightsaber that we'll go ahead and call Luke Skywalker. Here's a loose C-3PO figure.
On the toy's back is an Arco logo and "MADE IN CHINA".
This figure has more points of articulation than the Kenner C-3PO figure, as demonstrated in the photo below.
Personally, one thing I've always liked about the vintage Star Wars line was the lack of articulation; all I want is my toy to stand, sit, and be able to hold a weapon in front of them. I do like wacky action features (such as the creative ones found in the Masters of the Universe line), but I feel that a million points of articulation usually just gets in the way.
What this Arco toy does have in common with the Kenner figure is pegs on the bottom of its feet...
...and a resemblance to Threepio, of course.
The Spacewar toys were individually packed on a card with a painting of the particular figure in an action/ walking pose towards the top left. The figure itself and its many accessories (which vary for each figure, but includes things like a lightsaber, a mechanical arm, and a TV camera) are placed on top of a colored square that overlaps a star field.
It says on toymania.com that there's at least two different versions of the card that each figure came on (though I can't find examples of each card anywhere), the distinction being the corners. The bottom left displays either an Arco logo or a rectangle with a Woolco logo in it. The top corners on the Arco card are cut fancy to match the design that's printed on the card, whereas the Woolco card's top corners are practically 90 degree angles.
Although it actually doesn't use the Spacewar logo, the "Play Kid Moon Walker" looks right at home with the other toys in the series, and even comes with "Luke" and the landspeeder-like "Jet Rover".
While looking at ebay awhile ago I saw a role-playing gun toy with the Spacewar logo on the card. That was one of those moments where I was thinking, "Aw, man, I didn't think I'd ever be able to collect all the figures, but there's guns, too?!?" That's just how collecting goes, I guess.