It's beautiful. Totally agree on the flat-shaded aesthetic. A nice stylized low-fi without giving into pixel-art.
I'm always suspicious about simulation-driven games because they can get lost in the wonkery of it in ways that don't actually provide gameplay to players - my understanding was that Master of Orion 3 was ruined by this kind of design. But it looks like your "simulation driven" thing is about the citizens, which is wonderful.
Your current vids are very rural. Are you planning on getting into transit and bike-lanes and the like, or is this primarily going to be about roadways?