Rickton:There are two main mechanisms implemented:
1. "Bulk" simulation of the world.
Each small piece of the map (region) stores its population, how many units of each faction is there. Number of houses. Total wealth of the region.
The world is simulated by a few rather simple rules: there is population growth, unit transfer between neighboring regions, fights between enemy factions, if their people happen to be at the same region. Houses are built and destroyed. This is very rough and approximate simulation, but it is detailed enough to resemple civilizations growth and their wars with each other.
When the player is nearby, a region is genearaged from its seed, and units are spawned. If you kill anyone, that unit is subtracted from the region's population. In the background, this region is still simulated as a part of the big world even when the player is there, but latently, the changes are saved and applied when you leave the region.
When you walk far away from the region, the region is reconstructed together with all its units and items. All items are decomposed into wealth.
In this sense, the world is semi-persistent. About 10-12 regions around you are stored and simulated in detail, but they get decomposed when you explore new regions.
2. Heroes (or actors) are
persistent units, essentially like the player, they travel and fight mobs. Any mob (except domestic animals like cows) can be such a hero.
When heroes are in a region generated for detailed simulation, they is spawned together with other mobs, and they act like normal mobs, no difference there. However, when the player leaves, they are not decomposed entirely. They travel in the "bulk" world, fight with local units (their fights are approximately fake-simulated), they pick up items, choosing the best possible equipment they can find.
All of the above is already implemented. What I want to add are organizations of heroes (actors). They are going to be tree-like hierachies. Starting with simple local militia to fight neighbors and wild animals to governments and military forces. Actors-Merchants to sell stuff. Actors-Craftsmen, Blacksmiths, Engineers, etc. to make new high-quality items. Good to make some factions more inclined towards technology and dwarf-like traits.
The factions, btw, are random and generated with the world. In the biginning of each game, I plan to ask for the name of the world and the name of the player. Both will work as seeds. So, you can play in the same world as many times as you wish. And you can play the same character in different worlds. I think, it can be interesting to add the following feature: If your character dies, but the final goals are not achieved, you can continue playing with another character. It is not a simple respawn, b/c you start a new character, and you loose a lot of time. But if you was very close to kill the bad guy, your second character can finish the job, where the first failed.
P.S. I liked Game Hunter's video of your game Possession, never played myself, but it looked very interesting