Imagination of an open world.
I just realised you could do this in Sims 4, and I was impressed by how remarkable the landscapes really are.
Oasis Springs
Sunset Valley
It might not even that hard to mod an open world into the Sims 4, by allowing the loading of neighbourhood lots and removing camera limits within sub-neighbourhoods.
Side note. I would KILL for an option to control sims first-world style (similar to Grand Theft Auto),
where I can actually feel rewarded for walking around town and discovering new parts of town.
Or at least a mod to make the camera move faster when using arrows to move the screen at maximum zoom.