If you love the fantasy adventure of the Pathfinder RPG but really wish you could take your characters into space, then rejoice. A new setting, Distant Worlds, gives you an entire solar system to explore in your next campaign.
One thing you have to give Paizo credit for, they're willing to take chances. Distant Worlds takes Golarion, the secondary world where the Pathfinder campaigns take place, and places it within the context of an entire solar system populated by aliens who are even weirder than the weirdest dungeon creatures.
And while you can get to these other planets in "traditional" ways, with a spell or a portal, you could also ride a giant steel dirigible, or travel space in the belly of a massive herd animal.
And if you're undead, your spaceship doesn't need to seal out the vacuum of space at all. The Bone Sages of Eox sailing between planets with their faces to the void is one of the more compelling science-fantasy images I've imagined in quite a while.
To be sure, this is a book full of ideas and concepts. They are awesome ideas and concepts, but if you're looking for pages of hard rules detailing space travel or life on other planets, you won't find much. There's a short section on new alien races (and there are some weird ones!), and a handful of new spells and equipment. But 95 percent of the book is filled with descriptions of planets, the mysterious places you can find there, and the creatures who live in them.
That is certainly no criticism – author James L. Sutter has come up with some alien places in here that seriously blew my mind. My personal favorite is the gas giant Bretheda – although it has no real surface, creatures that appear aquatic "swim" through the maelstrom of the atmosphere. Apostae is a small world with an eccentric orbit, and beneath its rocky surface is a confounding mystery, an alien race called the Ilee who have been trapped inside their massive starship for so long they have no idea why they're in it or who they really are. "Sad and creepy" is a really unusual combination of emotional reactions to evoke even in a novel, much less a short gazetteer for an RPG.
Each planet includes several adventure hooks to help you tie things into your otherwise terrestrial campaign. Some of them have aliens visiting Golarion, others have your characters cruising the void, others involve large scale interplanetary conflicts that spill over into your adventures.
I'm generally a fan of more grounded RPG adventures, but Distant Worlds captures the weirdness and alienness of visiting other planets in a strange solar system so well that it's totally won me over. Certainly it could stand to be filled out with more game mechanics (I'd imagine the Ilee have some pretty bizarre spells and magic items), but it's planted a bunch of story seeds in my brain that have been slowly germinating ever since I read it.