A world filled with magic, albeit now limited after the gold age of the Highborn plunged into darkness after an event know as The Calamity. In pursuit of a never ending night the Highborn's efforts caused a disaster in the center of the content Ashrin . The magical fall out of the Ack'erat killed millions and left a giant crater while turning much of the land around its activation into desert.
Additionally, the Mortal Realm suffered the incursion of the creatures from the Shadowlands ; most notably demons. This Long Night, or Twilight as it's more commonly called, lasts 3 days each month and begins when the two moons align eclipsing the sun. The world seems to be suspended in time during Twilight as the corrupted magic of the Ack'erat warps the Mortal Realm dissolving the barrier between it and the Shadow Lands.
Nearly 2 billion mortals died during the initial 10 years after The Calamity before Mortals fully adapted and set up sanctuary cities with barriers that protected them from the creatures of shadow. It took another 10 years before the number of demons crossing into the Mortal Plane waned, a direct result of their drastically reduced availability of food. Many demons starved on the Mortal Realm and as such life outside of the Sanctuary Cities eventually became better but was still very undesirable. Typically, peasants are the only ones who live outside the Sanctuary Cities. They travel light and do their best to make it to a city during Twilight or find themselves testing their luck amongst the darkness.
There are those who make it their occupation to face the horrors beyond the cities protection and venture forth to clear the way for armies, caravan's, and other influential people after each Twilight. These would be your adventures, mercenaries, and monster hunters. Dangerous jobs for good pay, a good and exhilarating life that can be quickly ended if one is unfortunate enough to cross paths with a demon who remained on the Mortal Realm.