The Solar System is much cozier than here. The planets are closer together. Being in "space" is like being atop a high mountain. The air is thin and cold, but breathable and survivable, although you probably want an airship if you plan to navigate the luminiferous ether, and having access to an alchemist who can speed things along wouldn't hurt. Science in general works more like the way people in the 19th century thought it did. In fact, the culture and decor are pretty much Victorian as well.
The planets are more or less like nations, and interplanetary intrigue looks a lot like Ruritarian romance. Adventures are almost certain to involve at least one hop from one planet to another. In addition to humans, there are alien natives on every world in the system, some like flora and fauna, some fully sentient.
This genre is adjacent to 'rainbow fantasy'. It's normal for the protagonists to have extraordinary powers. And, although the fate of nations and worlds may be at stake, our heroes are unlikely to come to serious harm. For example, if they lose a fight, they'll almost certainly be captured and imprisoned, rather than killed.
One element I'd probably drop from these materials are the long narratives of space-flight. I'm not even sure how much I really enjoy reading nautical tales about tying knots and learning self-reliance; I know for certain I don't want to dwell on time spent in transit while I'm at the gaming table.
Novels
Arabella of Mars, Arabella and the Battle of Venus, and Arabella the Traitor of Mars by David Levine
Celestial Matters by Richard Garfinkle
Larklight, Starcross, and Mothstorm by Phillip Reeve & David Wyatt
Radiance by Catherynne Valente
The Revolutions by Felix Gilman
Sun of Suns, Queen of Candesce, Pirate Sun, The Sunless Countries, and Ashes of Candesce by Karl Schroeder
Graphic Novels
The Brass Sun by Ian Edginton and INJ Culbard
The Space Race of 1869 and The Moon King by Alex Alice
Games and Other Materials
Mega Man V (Game Boy)
Mickey's Space Adveture (Commodore 64)
National Geographic Atlas of Our Universe by Roy Gallant
Twilight Calling by Tom Moldvay