THE WORLD
Girl Genius is a (once print, now web) comic that updates every Monday, Wednesday, and Friday, dubbed a "gaslamp fantasy" by its creators, Professors Phil and Kaja Foglio. This term is similar to the more widespread "steampunk;" it was chosen due to the comic's general lack of the "punk" part, and a more fantastic setting than one that may be expected in a proper speculative fiction. The storyline follows Agatha Heterodyne, the Girl Genius referenced in the title, and her adventures in an alternate version of 1800s Europe. brassburg, however, starts many years before the current timeline, and does not require a potential player to read through the entire archive(over six years!) before applying. All relevant information is listed here, as well as the links at the bottom of the page.
Most of continental Europa is made up of walled cities ruled over by a Spark, and separated by vast stretches of wasteland too dangerous to travel through alone. A bloody war between Europa and a mysterious figure known only as the Other had raged for three years before ending, not with peace but simply with the Other's disappearance. The Heterodyne boys, a pair of folk heroes famous throughout Europa for their near-legendary adventures, disappeared soon after, presumably following the Other, wherever it went, in an attempt to prevent its ever returning. This, unfortunately, left the countryside without its guardians to protect it.
The most infamous of the Other's creations were the mind-controlling slaver wasps, insectoid creatures produced by a device called a hive engine. Those possessed by the slaver wasps become shambling creatures called revenants, sort of like zombies without the whole being dead thing, near-mindless and attacking people without discrimination. It's rare to see one alone; presumably it would be much easier to avoid or overpower a single revenant, if they did migrate across the wastelands by themselves.
Revenants are not the only dangers in the wastelands. It's not at all uncommon to run across dangerous monsters escaped from the nearest Spark-controlled city and giant battle-clanks run rampant; while there are people who live in the wastelands, they're typically poor and have to travel in groups. The smaller towns provide a bit more safety, but one shouldn't make the mistake of getting too careless just because there's a wall around them.
The city of Brassburg was, up until the war, rather unremarkable. It was of middling size, calmly lying in the foothills of the Austrian Alps, its citizens mostly cooperative and its crime rate relatively low. It was likely these aspects that began to attract people to it, before and during the war; what better place to ride things out than a walled city nestled in the hills? Of course, as time went on, more and more people got the same idea, and overpopulation, crime, and poverty became increasingly pronounced.
By this point, the city is nearly at capacity. Housing is limited; if you have no friends, or can't convince a stranger to let you live with them, you're pretty much out of luck. Sleeping in the streets at night is a dangerous prospect, but many simply have no choice.
There are a few advantages to the spike in population. For one, there are always jobs to be done; they may not pay very much, but it's better than nothing, and gives the citizens something to do all day to keep their minds off of all the problems the city is having. There's also a sort of solidarity involved when everyone around you is having the same issues. They may not be your friends, but you can usually count on helping one another through tough times, and you can always count on there being someone at the bar to share a drink with while the both of you gripe about the state of the world.