Cos is a fantasy D&D homebrew world that has evolved into something more than just D&D to me.
In the Continent of Calmireth, The Kingdom of Kings rules the west, the Legion of Athos rules the mountains, Firelight's Domain brews to the North, and the Altornie ignore the calls for help from all races. Calmireth is the setting of many adventures for many heroes. From the ashes of old empires new arise. Primal gods begin to stir and eldritch beings invade. The Juttan threaten borders of the half-orcs and the province of Dryakon. Country declares war on country, race on race, brothers declare war on brothers. This world is brutal, the weak do not last long while no one is there to protect them.
The Empire of Kings unified the land long ago, bringing peace and balance. All but the Firelight were conquered. When the Light Elves were almost entirely wiped out, the ones that remained fought back and brought dark magic with them. The seats of power have shifted between Kings, Firelight, Athos, and Laria throughout the ages. Constant war and racism between races have plagued the land, but there are still those who believe in good across the nations, looking to bring peace, one way or another.
The continent of Breven home of the Brev Kin is stuck in an endless cycle of war. What was once a great unified land now is split by race and religion. Each faction believing they are the rightful rulers and their religion is the true way. A land in the center of the world magic is low, but military tactics and power is unmatchable by the other continents. The divinely-blessed High Men believe they are the final race of beings in the world, while their creations the homunculi disagree. This war of the land is endless as they stray farther from the Truth that they all believe they have the answer to.
In the continent of Armeren is a land of mystery and legends. Disconnected from civilization and order, the inhabitants are always living in fear. The swamps and forests cover the land that the Swine Kin use for agriculture. The Armen Kin co-exist with the Swine Kin protecting each other from the mysterious forces surrounding them. Without contact with Calmireth or any other content they constantly feel alone and forgotten.
In Galan a southern continent away from most of the world an Empire grows like no other. The Glass Empire composed of mostly Elves and men use their dwarven slaves to mine the magical metal of glass builds huge cities and advanced weapons to conquer every nation in sight. A strange environment this land is, an error sits on the bottom of the continent, a land of darkness where it is never day, only night. The minor nations south of the Glass Empire are proud and strong, trading amongst each other or constantly fighting for land, this continent is not exempt from chaos.