What The Drek Is Going On? Hoi Chummers... You want to know what's going on in Shadowrun: Corporate SINs? That's a big question with a very long answer. But you don't have the time for long answers! You want to know NOW! Fine, here's the quickest explanation I can give:
The 6th World Edit
It's 2077, and man, have things gotten weird. Massive Corporations control everything, Dragons fly across the sky to attend board meetings, and the lady next to you on the bus is an Ork who could turn your insides out with a simple spell. You don't spend dollars, you spend Nuyen. That's New Yen, but that space takes too long to pronounce in most 6th world circles.
The Corporation thing happened because governments decided that corporations had the right to decide their own laws, on company property, in a little legal thing called extraterritoriality. Suddenly, the largest corporations weren't subject to the laws of the countries that contained them, which meant they could do pretty well whatever they liked. And boy did they! The ten biggest corporations, which make up the Corporate Court, get to make the most decisions on this planet... hell, on this solar system: After all, Evo has a lot of people and equipment on Mars.
And the Dragon/Ork/Magic thing? Turns out, the 5th World: the one you live in? It was just a phase: one that happened to not have any magic. In 2011, magic came back, in a big way. Dragons, humans turning into metahumans: Elves, Dwarves, Orks and Trolls, and more. And the humans that remained humans welcomed them with open arms! Hah! No, actually humanity freaked out and decided that there was a new type of racism in town, and took every chance to try to suppress these new metahumans. Of course, even in the 6th World, nature has a way of balancing things. Magic meant that some of those metahumans were backed up by magicians, shaman, spirits and more. And technology meant that those with the ability to control it had the means to resist those without.
The Seattle Metroplex Edit
Here's another thing you need to know: The countries you 5th Worlders live in and love? Gone! Or changed forever. In the good ol' US of A, corporations decided that they needed what little land Native Americans still possessed, and so they took it. It almost worked, but when magic came back, those Native Americans were ready: with enough magic to erupt a few volcanoes, it wasn't just the political landscape they changed. What remains of the United States and Canada is divided up into several countries. One of them, The UCAS, consists of the Northeastern former USA and eastern Canada, but oddly enough, it also includes the state of Seattle: an area covering a good portion of what was once Eastern Washington State. Surrounding the Metroplex on all sides are the Native American Nations: specifically, the Salish-Shide council. The war is long over, and things are mostly diplomatic, but Seattle works hard not to tick off the Salish-Shide: there are still a lot of volcanoes in the area that most Seattlites would rather not erupt.