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?
Transit should be outrageously expensive to add. (see the recent subway expansion in New York and in San Francisco) It should be outrageously expensive to operate.
Transit should shut down often for floods, strikes, the "wrong type of snow", "leaves on the tracks", crowds of people (good job San Francisco, LOL), maintenance, terrorist attacks, and many other random reasons.
Transit should increase crime.
Transit should go to the wrong places. You ask for it to be installed where it is needed, but instead it ends up a mile away because that was where it is possible to build.
Similarly, pollution was unreasonable. Coal power may be dirty, but SimCity made it absurd. There was also the nuclear plant explosions that pretty much never happen in the real world. Both the failure rate and the failure consequences were way above normal.
I will think about becoming a patron... .