One of the most popular Pathfinder books is Distant Worlds. It's also one of my personal favourites (and one I really ought to review sometime—I will add it to my increasingly long list). Distant Worlds moves beyond Golarion to explore the other planets in Golarion's solar system. In doing so, it introduces not just new and exotic locations, but also scores of new creatures and races (most of them only described and not statted out). Not surprisingly, many people have wanted to play these new aliens in Pathfinder games, and many have since had stats published in Bestiaries and other supplements. However, People of the Stars is the first book to take a close look at a science fiction-type races for the purpose of using them as player characters. On top of that, it introduces a number of new options for characters in games involving aliens and space travel.
People of the Stars looks at four races in detail: androids, kasathas, lashunta, and Triaxians. It also has brief coverage of several other alien races. Like most Pathfinder Player Companion volumes, the focus is on mechanical options, with only a small amount of background information. The exact amount varies from one race to another—androids get half a page, for example, while kasathas get barely two paragraphs. In general these days, I tend to wish that there was more background information and fewer mechanical options because the game has enough options already; however, in this particular case, the game doesn't have a lot of options for outer space adventures, so the volume of mechanical options makes sense. And despite all that, there is still quite a bit of good and useful background information scattered throughout the book.
Each of the four main races gets two pages of detail. These pages include the base racial traits along with various other options, such as new feats and archetypes. Each race also gets a pair of race traits (not to be confused with racial traits). I find the inclusion of kasathas in this book an interesting choice, as they've not really been a part of Golarion previously (although undead kasathas do appear in Fires of Creation). Kasathas first appeared in the Advanced Race Guide (which is a setting-neutral book) as an example of a race created using that book's race builder system. As a race with four arms, they gain quite a few mechanical benefits over other races (thus their high 20-race-point cost in the Advanced Race Guide). People of the Stars presents them without any warnings about power level, as if they are on par with the other races, which I find a bit of a concern.
The kasatha section also provides a new ranger archetype, the bow nomad, which provides kasathas with a new trick for their four arms—the ability to use two bows at once. Not only is this a pretty powerful ability, it's also one that's really hard to visualize without everything getting tangled up. Even the picture provided on the page is forced to have the kasatha pointing her bows in different directions, and the pulled-back bowstrings still end up overlapping (and probably interfering with each other). Of course, this is a game where characters can do all kinds of stunts that would be impossible in the real world, but usually it's still possible to imagine what these stunts look like. This is one of the few times I just can't wrap my head around what it would look like to use an ability. At any rate, while wielding two bows is a pretty powerful ability, the text does, thankfully, draw attention to the fact that, since bows are not light weapons, they take the greater penalties for fighting with two weapons (-4 to each if the character has the Two-Weapon Fighting feat). Overall, I'd caution GMs to think carefully about allowing kasatha characters (whether with this archetype or not) alongside the core races or even the other races in this book—though a party of all kasathas would be workable.
The other three races are at a power level much more in line with the core races, and they get a number of interesting new options to go with them. Androids have several new feats to choose from, including Nanite Disruption, which allows androids to short-circuit electronic creatures like robots. Lashunta gain a new cavalier archetype (the Qabarat outride) and Triaxians get a druid archetype (the season keeper). This latter archetype ties in with the fact that the Triaxians' home planet, Triaxus, has seasons that last longer than Triaxian lifespans. As such, most Triaxians never see a change of seasons and those that do may not know what to expect (especially as Triaxians undergo physical changes when the seasons change). Season keepers help guide Triaxians through the transition from one season to another. I like this kind of archetype much more than something like the kasatha bow nomad—not because of relative power levels, but because this one ties into the setting and the society of its associated race much more. It offers PCs new mechanical options while simultaneously having a clear place in the world, something the bow nomad doesn't. (Part of the problem also comes from the fact that kasatha are just sort of tacked into the setting and don't really have a society/culture to build on, whereas Triaxians are already much more developed.)
People of the Stars also devotes two pages to brief descriptions of five other alien races: formians, kalo, shobhads, Vercites, and Ysoki rat-men. These descriptions focus on background information and do not contain rules details beyond mentioning what other books you can look to to get rules information about them. This is a good way to acknowledge these races and additional options players might have, without having to use up too much valuable book space.
The races take up the first half of the book. The second half looks at diverse other topics, such as gravity and spellcasting in a vacuum. A couple pages provide brief looks at places beyond Golarion's solar system, while another two discuss the Dark Tapestry, a realm of “nothingness that spans the blackness between stars.” The Dark Tapestry is where the Outer Gods (from H. P. Lovecraft tales) dwell and where, long ago, the god Dou-Bral was corrupted into Zon-Kuthon. There is also a look at the locations on Golarion that have seen the most contact with beings or forces from other worlds (places like Numeria and Osirion). Of course, there are also new spells, new space-faring and astronomical equipment, and more feats.
Throughout the entire book, on almost every second page, there is a sidebar with information on one of the planets in Golarion's solar system. These sidebars go in order from the sun all the way out to the last planet, Aucturn. Each sidebar provides basic details such as the planet's diameter, mass, and gravity, along with general information about the planet (or star in the case of the sun, or asteroid belt in the case of the Diaspora). Each sidebar also contains a new trait (generally a regional trait, but sometimes another kind).
My favourite parts of the book, though, are the maps of Golarion's constellations found on the inside covers. The inside front cover shows the constellations of the northern hemisphere, while the back shows those of the southern hemisphere. It's this kind of colourful detail that I love seeing in Player Companion and Campaign Setting books. They are the sorts of things that give insight into the lives of people in the world and truly bring the setting alive. The centre two pages of the book contain a map of the solar system showing the relative positions of the planets (though not to scale).
Overall, People of the Stars is a great book for people who want to add a little bit of otherworldliness to their games. It's not a book for everyone—particularly for those who aren't fond of mixing fantasy and science fiction. But for those who do like that sort of thing, it will be invaluable, providing lots of new options to make the game truly alien.