Arde is the mortal realm of "Rule of Chaos" a 5E extension all about playin mighty demons.
The world of Arde will go through 7 eras. Primeval, Ancient, Medieval, Rennaissance, Industrial Revolution (Steam Punk), Modern Age, Sci Fi (Cyber Punk).
In all these eras magic and demons are percieved differently and have a different influence on the world. We already developed the concepts of those eras including inhabitants, politics, relationship between science and magic, ...
We start with the medieval time, in which demons are percieved as evil due to the strong narrative of the curches. Nonetheless there are parts in this world, where the influence of the churches of heaven is not so strong.
The challenge for demon players is here to not blow their cover carelessly and unleash their force when the time is right.