A game idea has been haunting me for over 20 years. Its title has ranged between "World simulator", "Bottom-up Civilization", "Multi-player Populous" and "Self-sufficient Community Simulator", but the general idea has remained pretty much the same. Imagine non-extractive but technological human life in a world where the environment actually reacts to what you do.
I've started to implement the game several times, but it always fell apart at the world-shaping stages (climate/weather most often). Now I've started it yet another time, this time focusing on the gameplay/interface layer first. I've also been taking ideas from Dwarf Fortress and RimWorld even though my original design took somewhat different routes.