An open world, survival, party based rpg. Survival elements are light and focused away from micromanaging every crop placement and every floorboard. Player parties build cities, forts, roads.
It's like: Minecraft without the block gimmick or detailed building capabilities. Skyrim with more playable characters in a player built world without a set storyline. Valheim without the heavy focus on survival elements or linear progression. Party management and diversity like a tactics RPG.
I'd love it to have several for game loops to bury yourself into. City building, character builds, crafting, gathering...
And multiplayer capable, self hosting if desired.
This is a pipe dream. A game that huge is too difficult to make for a game that wouldn't have larger appeal.