I'm not 100% sure what the game play will be; I've enjoyed the survival aspects of a game called VintageStory, but I also have my own concepts that I want to flesh out and develop. This document will contain a mess of ideas and notes, but I might clean it up at some point if I start working on this more consistently/seriously.
I've had an idea for a survival type game that I'll try to quickly describe. I like the world in Skyrim, the player traveling around to towns/settlements, interacting with NPCs, crafting items, and fighting bandits in dugeons, etc. But the one aspect I want to focus on is a "world-wide" economy run by the NPCs; instead of there being a "finite"/small number of NPCs, I envision there being 10,000s or 100,000s. Obviously they would need to be procedurally generated to some extent, but for a campaign, there could be hard-coded characters for story development and such. Instead of merchants selling items from their "inventories" for pre-determined prices, the items would have to be produced by an NPC somewhere, traded and transported, to be available to the player. For example, imagine you the player burns down a bunch of farm fields for fun; this would impact the economy of the nearby town, the supply of food would drop, the price would rise, and NPCs might even start starving, because of the players actions. I realize this game world would be a challenge to implement efficiently, and that's part of what draws me to it. (I think this might have some overlap with the game Dwarf Fortress, but I haven't really played it.) From this core-economy system, I envision the player travelling through the game world, and doing things to influence the politics and economies of small villages/towns, all the way up to large cities/kingdoms.