I'd recommend very black and white villains/heroes. That was a big part of the sci-fi of that era. Ming the Merciless for example, there wasn't a lot of nuance to him, he was just simply the bad guy. He destroyed and enslaved simply because he wanted to.
So the best thing I think you could do is use that same concepts your game. Make the PC's heroes of great virtue and the bad guys despicable villains that are irredeemably evil.
Then add the aesthetics like you mention and you'll likely go a long way to getting that fee.