Setting
The year is 2035, the world has advanced significantly in many fields of technology. No laser guns or cyborgs yet, but all the simple technology has advanced to new frontiers. Fuel and energy, for instance, as well as the technology needed to create an artificial land mass. Antares, the first international city built upon the first perfected artificial island in the Atlantic Ocean in international waters. Multiple nations and multibillion dollar corporations worked together to build it in an effort toward peace, and profit in some cases. The city contains everything from casinos to farm lands, and presented a number of work opportunities, both blue and white collar. Of course being in international waters would make it the prime target for criminals, like pirates. And so security is handled by mercenaries, former police, and former soldiers from around the world to serve as the Defense Force and the Security Force. To deal with external threats and internal threats respectively.
Story
Now that would be telling.
Territory
While most of the city is free reign for most, some specific areas are held with particular strength by a set faction or supernatural race. This doesn't mean others can't go there, but it does mean they're less likely to have support nearby and may run into trouble with others.
List of Territories:
Vampires
Vegas District - The Kindred have a fairly strong presence in the Vegas District due to it's constant activity and reckless people.
City Library - The Ordo Dracul, a Vampire Covenant, has it's base of operations under the City Library.
Mages
University Campus - The Awakened have a decently powerful hold in the University, conducting a lot of the Consilium's meetings here.
Werewolves
Lake and Forest - The Uratha have a near sole presence in the Forests outside the city as few others have any interest in them.
General Information
This is general information that most who know of the supernatural will know about, but not everything.
Ghosts - The remnants of the deceased. They exist in Twilight as ephemeral beings. Ghosts can, however, manifest into the physical world to affect it, if they have the power to do so, but will remain ethereal. Only blessed items or magic can harm them, be this through holy power or simply the will behind the act of 'blessing' itself. However one with strong will and the know-how can ward it off or even banish it altogether. Ghosts cannot travel far from their Anchors, that which binds them to the world, be it person, place, or thing, of which there can be many. Many Mages believe that ghosts are simply ephemeral imprints of the beings they used to be. Ghost can possess various powers called Numina used by channeling Essence.
Twilight - The state of existence for ephemeral creatures. Ghosts can be found here, as well as the remains of certain objects that have left behind an ephemeral imprint in Twilight. Spirits can also be found here, though it is taxing for them to exist here. Any Demons in the world also exist here.
Spirits - The natural denizens of the Shadow Realm and can take numerous forms, such as spirits that embody inanimate objects, living things, emotions, concepts, and even events. They can be created by strong emotions, or the creation of new objects or life. They behave like what they embody, a wolf spirit hunts and toy spirits play. They grow stronger by consuming other spirits, usually ones that reinforce what they embody, such as the wolf spirit consuming spirits of prey animals. They have a hierarchy as well, ranging from weak, newly born spirit, to spirits with power like gods. Spirits, like Ghosts, also possess Numina.
Shadow Realm - A warped reflection of the material world where everything is alive and significant events in the physical world may create reflections in the shadow that exist long after the original is gone. The Gauntlet prevents passage to and from either place, except in places known as loci, or a locus, where essence bleeds into the world and can serve as a bridge. Due to this, very few even know of it's existence.
Underworld - Beneath reality lie the cavernous deeps of the Underworld, also called the Great Below, the home of the ghosts whose ties to the living world broke. Some places in the world of the living are closer to it and form cenotes, places, where the dead haunt the living. This place is not Hell, but neither is it Heaven, and most ghosts are not happy to be here as they can no longer attempt to complete their business from beyond the grave. It is not a safe place for the living to venture, for some ghosts are sorrowful, some are vengeful, some are mad, and all are desperate. The traveler is always moving downhill or uphill, never flat. The subterranean halls are bleak, but often punctuated with bright colors, reminders for the dead of the living world. This place offers many dangers but many rewards. The only way in is through finding and opening an Avernian Gate, or by finding a way in through the Shdow. Various rivers of mystical powers can be found, usually by luck, and many Dominions exist with with the deeper ones ruled Old Laws enforced the Kerberoi, Deathlords, who rule a Dominion.
Demons - Some claim they come from Hell, others that they are simply dark spirits, and some even that they are twisted ghosts. But one thing is certain, they are selfish and cruel, and they can play mortals like violins, tempting them with their darkest desires. They come in many forms, but are always tied to a Vice; Wrath, Pride, Envy, and so on. They grow stronger by tempting mankind to sin, mostly in their Vices, and by damning souls to the pits, if they do indeed come from Hell, but even that in unclear, just as it's uncertain if it's the traditional biblical hell. For we know they could be born from us, from our Vices and the darkness within could even be the Hell they come from. Demons can be summoned to perform services and grant powers, but it always comes at a price. Want to be the prettiest girl in town? Then you have to find a gorgeous girl and take that away, permanently. And not by death no, you have to mutilate her and take that beauty away, then it's your's. Of course everything is negotiable, maybe you just give up something relevant. Demons, like Ghosts and Spirits, are made of ephemera and exist in Twilight when not in Hell unless bound to or possessing a person or thing in which case they reside in said person or thing.
More information can be found in these two places, with one filling gaps in the other. Be certain to look only in the World of Darkness and not the classic version or the other games like Scion and Exalted.
http://wiki.white-wolf.com/worldofdarkness/index.php?title=Main_Page
http://whitewolf.wikia.com/wiki/Portal:World_of_Darkness