The 100 Kingdoms is a large realm. Within its borders there are a myriad of kingdoms, ranging from the key powers to petty kingdoms that rule little more than a valley, or a stretch of river. Any man may set himself up as a petty king, provided he can defend his claim and placate the populace he calls his subjects. The core theme is potential. Anything can happen. Mortal men and women can become semi-divine, demons can become ascetics and pray for enlightenment, and danger and daring are never far from hand.
Mood is as variable as the storyteller wants it to be. It can be played as horror where the PCs are set against an infestation of demons, or an angry swarm of undead boiling up from the fecund earth.
It can just as easily be epic fantasy, which is the general path that is going to be followed. Swords are trusted allies, shields indispencable, and magic frightening and strange, the purview of wise men, sorcerers, and mystics. Heroics, both romantic and dramatic are preferred.
The gods and the demons regularly practive the power of magic. Wise men, sorcerers, mystics and magi practice the same arts with differing levels of skill. Magic is feared, and magic users viewed with a level of distrust. Many know all to well the damage caused by magic, for the demons and unclean spirits use it at will. Sorcerers are accused of fornicating with demons to gain their powers, while mystics and wise men are feared for their lack of humanity, or empathy. The Low Magic thread should be consulted for the common level of magic available. Powerful sorcerers are relegated to the roles of Prime Antagonist, and prime benefactor. The source of their power secret, their ages unknown as their agendas and plans.
Technology in the 100 Kingdoms is comparative to early renaissance period. Most of the outer lying areas are further behind, but use of iron is common, printing presses are begining to appear in the core metropoli, and medicine is available in the form of alchemists and herbalists. Guns as we would know them are not present, but paper rockets, iron bombs, and pot-de-fers can be found in the workshops of enlightened smiths and alchemists. Gunpowder can be made, but it is smoky, unstable, and without the ability to turn an iron barrel, there are no guns, cannons, etc.