6 themes of the Old Frontier

Bogeyman's Cave and Throne of Salt (among others) did this thing already, so go read those ones. Once you're done with those, with no further ado, here's my setting flavour waffle!

Brief Introduction: The Old Frontier

The Dread Emperor rules, has ruled, will always rule from the Mightiest of Cities, Babylon, seat of the Throne, and from his Basalt Throne he stretched his hand across all the Empire and beneath his benevolent gaze, mankind flourishes.
In theory at least.
In reality, the Duchy of Brockenwold is far, far from the vital beating heart of civilisation. The frontier has stood here for centuries, ebbing and surging back and forth, cities and towns blooming and wilting in turn, no-one even knows anymore if the ruined cities in the mountains are the corpses of Imperial cities or the ailing remnants of even older ages. This is just as far as humanity can go, there is nothing worth having beyond the Brockenmoors or the Saurmachts. Some things are certain though.
Something isn't right about the Duchy.
There are (utterly spurious of course) claims that monsters roam the moors, and beasts and creatures of legend, things that cannot and should not be, roam the Eldenwode, and there are even whispers of Gods.
Someone needs to sort these out, and put the old tales to rest.

1 - Mankind is Old, we have left many ruins

Many are the ruins of ancient times.

The empire of all humanity is ancient beyond reckoning, and its borders have shifted and ebbed like tides over the many millennia. In the quiet and forgotten corners are the dead remnants of old cities and castles and towns, obviously ancient, but only the most learned will be able to discern if they were the homes of civilisations of previous ages, or merely imperial cities that were lost in the latest spate of disasters.

2 - The Gods are Dead, but we are not alone

All man has left are Saints and Angels.

It is well known that the Gods are Dead; none dispute this. Without them, demons and devils and monsters and wicked men prey on the souls of man with ever growing audacity, but there is hope. Some few of the peoples of man are worthy to walk the Path of Saints and inherit the leftover scraps of their Divinity and ascend with power to the heavenly battlefields. So to do the God's attendant angels, now masterless, mass in heavenly hosts to battle against the dying of the light. These are the beings that men worship, to defend their living souls from being stolen in the night.

3 - The World is Alive, and yet Dying

The spirits of the world take many shapes and forms.

All things have their spirits, they are all alive; not quite in the manner that you or I are, but alive they are, and they all have their own minds and goals and agency. The druids and shamans and rangers of the world know the old ways of man, and can yet speak to them, and interact with the souls of mountains, and preposition the hive-mind of the forest.

And yet, the Sun wanes in the centre of the universe; the earth will not survive its death, and so it plans, and hopes.

4 - The System is Broken, and The Man is not your friend

Well, maybe not exactly like this, but maybe more of your nobles should be Skellingtons?

His Dread Majesty dwells far, far away in Holy Babylon, and his agents are scattered and few.
The Duke of the Frontier is corrupt and fat on the harsh, harsh taxes he extracts from the people.
The Baron of Brygge is a heretic, a demon-worshiper, and dreams of rebellion.
People in power are very rarely on your side, and will usually at best be out to use you for your abilities if they do seem to be aligned with you. There may well be a few that genuinely are good, but they are few and far between. Hold them close.

5 - Magic is Everywhere you can't see it

The Cunning Folk know all kinds of secret, simple magics.

Magic isn't common, but there are always wizards who dwell in high towers just over the next hill, shrines to ancient spirits with pools of healing water, and you can never tell when your neighbour might be one of the Cunning Folk, and have a talisman to heal the sickness that has settled in your gut.

Most people will never see magic, but then again most people will never visit more places than they have fingers, and few will go to the lost and wild places where magic still waxes strongly. Most people don't even believe in monsters for heaven's sake.

6 - In the end, there is still hope for the future

All shall be well, and all shall be well, and all manner of things shall be well.

The world is bleak, but there is still hope.

The sun is not yet dead, there are still Saints to defend the souls of man, there are still heroes.

Perhaps you'll even be remembered as one.