You get XP for surviving. Every day you live, you get 100 xp.
If you have a thief in the party and they steal stuff, you all share the XP for that. But otherwise money has little real value. That’s why you leave it piled up in rooms. You take things that have use.
You start with no food and no water. The fatigue and food rules are the same as in 5e but moved to the front of the book as they are more important.
You begin in the middle of a map instead of on the edge. Maybe you need to explore the map or maybe you already know whats in it and played a part in creating it, still not sure about that one.
Around the edges of the map are single 'dark' hexes. These all hold different human communities. Each human group is based on a particular human archetype. Tang China, Conquistadors, Zulu Empire, Mongols, Crusaders etc. This gives each one different powers and abilities.
If you do nothing and no not attack each hex, they grow. Some grow fast, some grow more slowly and are more heavily fortified. Some, like the pseudo-Mongol one, move around quickly. 'Explorer' hexes can turn up randomly on river banks and shorelines.
You must attack them to stop them growing. Each culture works differently so you have to find out how to fight it. Some are highly centralised so if you take out the main guy then they fall apart and don't come back for a while. Others are faith-based so you have to destroy the religion. Whatever it is, you have to find a way to stop the culture growing. (Just killing everyone should always work, but there are a lot of them.)
There is never enough time to stop them all.
In these situations, villages and fortifications take the place of Dungeons in a normal game. Like mission one is 'take down the village of Homlet'
|Where would you attack first?|
You get XP for retarding or removing human cultures, but they would have to be specific rewards for each culture so PCs were incentivised to think of cunning solutions for getting rid of them.
So your map ends up looking like the spokes of a wheel gradually infiltrating into 'your' territory.
To take out a human culture completely, or at least retard it for generations, you need to go for their capital city. That's like a level 20 mission. Orcs fighting a city is like humans fighting Cthulhu.
As well as fast-growing humans there are Elf hexes and Dwarf Hexes. These don't grow, they just stay in place and cause you trouble. They are hard to get rid of and provide a jumping-off point for Adventurers.
Burning Rivendell is a high-level mission.
If you have a Dungeon, its one the group creates themselves at start of play. Some kind of microscope-lite game, or a points-buy system. That way it bonds the players to the space, it becomes 'theirs' and they will want to defend it. Its somewhere you can go to be in *slightly less* danger but sometimes adventurers will try to come in and take your stuff and you need to trap and kill them.
A bunch of Orcs and Goblins trying to take down a high level adventuring party is a bit like humans trying to take down a Kaiju, you have to separate them, wear them down and take them out.
I am not sure what to do about the Dungeon 'Boss'. Having a scattering of individual high-level monsters around may make the forces of chaos too powerful, but it gives you someone to get missions and stuff from, and who will also threaten you and make you do stuff. Also, other peoples dungeons are not necessarily allied to you so you can still invade those and do what any normal D&D party would do.
Plus other tribes of non-humans are not necessarily friends so subverting, destroying, evading or commanding them could be a mission.
Also everything that is dangerous to adventurers, ie Trolls under bridges, spiders in the forest, is still dangerous to you, unless you know those particular Spiders or that particular Troll.
The whole thing should be kind-of inside-out from a normal D&D game. Instead of being free agents, you possibly have a boss. Or maybe at least one of you does. Instead of having some food and money and nowhere to stay, you maybe have a whole dungeon you can use that you know every inch of because your player helped to build it, but you have no money and no food at all so you are starving to death from day one.
Instead of starting from the edge of the map and going in towards the unknown centre, you start at the partly known centre and do stuff towards the edge. Instead of gradually getting a larger world and being able to explore more, you are gradually hemmed in as those black human hexes proliferate and work themselves deeper into the wilds.
You never stop having to get food and you never stop getting attacked but enemies are also food so that solves that problem.
Whole thing would be like a weird mix of Microscpe, Apoclaypse World, 5e and Blood Meridian.