|Mars with an Arctic Ocean, Image by NASA|
This got me thinking to science fiction set in our own solar system - primarily in RPGs. It's not a particularly common setting, especially once you remove retro style games which focus on a pulpier version of the solar system such as Space: 1889 and Rocket Age. Those are wonderful games, but I'm talking games set in a slightly harder setting.
Off the top of my head, I can think of a few - many of which I've minimal familiarity with. The one I know best is probably TSR's old XXVc RPG, published in the late 80s and early 90s. It gets a fair amount of negative attention, largely due, I suspect, to the fact that heirs of the John F. Dille, creators of Buck Rogers, were in control of TSR and dictated this game be made. With that caveat, I do feel it to have been an unappreciated game - looking at the credits of the game and its supplements I see designers like Mike Pondsmith and Ray Winninger. It wasn't an especially hard game, with massive amounts of genetic engineering and some pretty advanced propulsion systems, but it made the attempt to at least feel grounded in the real solar system. Essentially, Earth has become quite the wasteland in the aftermath of nuclear warfare and ecological collapse, with a terraformed Mars being the superpower in the system.
Other games grounded in our solar system, games I'm less familiar with, include The Mutant Chronicles, Jovian Chronicles, Cyberpunk: 2020, Eclipse Phase, and GURPS Transhuman Space - the last two having strong elements of transhumanism - going beyond humanity with your mind being software. Though its default setting is an interstellar empire, most incarnations of the Traveller RPG give a thorough overview of interplanetary travel.
One item I like, both from Mutant Chronicles and XXVc, is the idea that the Earth is used up. It gives a heck of an incentive to be out there in the unfriendly environment of the solar system - and it really is a hostile place. Earth is a great place to live. We're used to the gravity, the atmosphere shields us from the worst of the sun's radiation, there's food pretty much everywhere.
Off the top of my head, I'd say there's a number of challenges to be overcome and a number of things you need in a solar system-based RPG. Since you're avoiding the pulp connotations of magic rockets and exotic substances like Space: 1889's liftwood, you at least need to give some thought to how expensive it is to leave the gravity of the Earth. Look at the Apollo missions to the moon - a whole lot of fuel and propulsion and just a teeny tiny bit of cargo and passenger space. Generally speaking, most settings do assume some pretty big advances in rocket technology and it is also reasonable to make use of concepts like the space elevator or the skyhook to make it cheaper to achieve orbit.
You also need something to do. XXVc made Mars the "bad guys" of the solar system, making life difficult for people trying to earn a dishonest living and providing an enemy for those seeking Earth's independence. Mutant Chronicles adds some esoteric elements like the Brotherhood and the Dark Symmetry and have hobbled the "thinking engines" of mankind. Eclipse Phase featured an AI that almost destroyed humanity and the aftermath of this war against humanity left behind wormholes known as Pandora Gates. This avoids the standard "ooh, easy FTL travel" by making passage through such gates often fatal and usually one-way.
Looking through some of these random thoughts I've posted, thoughts I might explore further at another point, I see that while grounded in reality, the games that appeal the most to me make some bold decisions with their backgrounds, going well beyond "well let's calculate your delta-v based on the fuel you can burn..."