Sky d6 is a role playing game occurring in a devastated world. In 1939, the white dawn catastrophe nearly destroyed the earth. Small piece of land are still present. The only way to travel from what is left of a country to another is by plane. Commerce, smuggling, negotiation and wars all depend on airplanes.
Sky d6 is very similar to a space opera game: a lot of empty space between the habitable planets. Plane combat is deadly; crashing between island means certain death. The heroes travel from one place to another, fight villains, attack enemy fighters and try to repair their ship, with a wrench and a hammer, while in combat with an enormous airship.
Yet it is still the earth we know. The French are still French. The British food is still bad and its beer is still great. The Nazi party is present in Berlin. You already know most the settings and you already understand how the technology works.
Concerning the Space opera genre.
I love space opera. But no matter how cool it is, there is a number of weak point to the traditional Space opera genre.
Raining On Planet Mongo - Each planet-of-the-week has one primary climate and terrain type. So we see ocean worlds, desert worlds, ice worlds, prehistoric jungle planets, planets that have been developed into a single city. But rarely a world that displays the sheer variety of our native Earth. Why, simply because exploring a real planet is a huge task. In facts, in order to have a different setting: difference in climate, culture or language, you don't need to move a light year, a couple thousand miles is enough.
G-Forces? What G-Forces? - Your average atomic-powered rocket-ship can accelerate to fantastic speeds without blasting the pilot's eyeballs out his backside. Super high speed are needed because the real distance between star system is astromonical. If we scale down the distance (flying from country to country), we remove the need for faster than light travel.
Technobable: it is impossible for a player to diagnose or just understand the consequence of a technical problem. The warp drive is unaligned, what to you do? The Quantum transmutational tachyon-powered toroidal flux is no longer graviton-protected; how do you repair such thing?
The Galactic Navy in the 30th century is a lot like the Royal Navy in 1940: Admirals and midshipman. Cruisers, frigates and dreadnoughts. "By God, we'll pound the hell out of them, fire all batteries!" Grease-stained engineers. Gunboat diplomacy. Salutes, ceremonies and sabers. The morale of the crew. "Breach! Seal the hull and prepare lifeboats!" Building a career and winning medals. Wild devil-may-care tactics. The respected opposition. All those don't belong in space, they just belong in 1940.