This is another interesting campaign method - copypasta from the cult of ORE google group
One of the things I did, that has worked really well, and that I
recommend to all GMs, to really help flesh out the world and to make
sure that the players would be really invested in the setting, was to
turn over the conceptualization and design of more than half of the
city's NPCs to the players themselves.
I came up with a huge list of what I call "NPSeeds," to give the
players to water, feed and cultivate into a more fully developed
concept.
A Seed might read: "(Normal) Elementary School Teacher. Has noticed
some odd occurrences around the school of late. Just recently started
having nightmares, as well."
Or: "(Sorcerer) Small time drug-dealer. Has recently completed his
training in Conjuration (Daemon Magick) and has started using it to
get ahead in their "business." Things may be going too fast, and it's
starting to catch up."
Or: "(Meta-Human) Mail carrier. Just a few days ago discovered an
ability to phase through solid surfaces, (ie. doors, walls, floors,
etc.) Now, maybe they can do something about that crooked pastor at
the local church whom everyone is fairly certain has been trafficking
in Daemon business."
I came up with fifty of these little blurbs, and sent ten to each of
my five players. The player then went wild with each little concept
and came up with anywhere from a couple paragraphs to a couple pages
of backstory for each one, extrapolating a fully-realized character
from each seed, and sent them back to me. Then, each player was sent a
"Target Package," of ten other seeds (that they hadn't worked on,
themselves.) Their job with that target package was to come up with
one or two "twists" or "complications" to monkey-wrench the NPC in
question. They did this, knowing nothing about the specifics of the
characters in question, having only seen the "Seed." For example the
player who got the School Teacher in their target package would come
up with a very general complication like... "They're having an affair
with their school's superintendent AND a student." They then sent
these Target Packages back to me. Then, I took the finished,
cultivated Seeds, applied the Complications from the Target Packages
and wove the various characters into a huge, sort-of cat's cradle of
interconnected relations throughout the city (campaign takes place in
Seattle, WA.)
So now, what we've got is a very rich, detailed setting, full of
little relationships and situations going on all over the place that
the players are really invested in, because they had a direct hand in
creating it. And nothing is spoiled for them because, while they may
have detailed a given character, someone else screwed the character's
neat little situation up with a few complications and then I, as GM
developed the situations and circumstances that connect each NPC to
the others. So, it's still a place worthy of exploration, while
simultaneously giving the players a sense of recognition and creation
in the world.
The best part is that it reduced MY work significantly!
Anybody running a campaign with a persistent "home-location" city, or
territory, should try this. You'll be blown away by the results.