I recently heard about a short story by a French author about a map making-obsessed country who covered their whole country with a 1:1 scale map. For years I've had the idea for an indie game about trying make it from one side of the USA to the other with a crappy car and little money - basically a modern-day reimagining of Oregon Trail. However a challenge would be rendering interesting buildings and cities. So something I thought about is what if the game also uses the idea of the whole country having a 1:1 street atlas map draped over everything? You could give hints of there being buildings and other interesting things peeking through rips in the map, while most of the modeling / graphics is really just open street map data textured over a height map.