Outside the walls of the domes, where the scars of nuclear devastation show.
Not everyone calls them the Wastes or Wastelands, but within the city walls it's generally the name for these areas. Abandoned, broken down, destroyed buildings and settings, remnants of small towns, the like.
A large portion of areas look dead, some practically barren-- but there is still life seeking to reclaim. Plants, Units, Transfers/Synths, those that escaped the cities or somehow managed to escape the destruction.
Often, in abandoned areas, you'll find people trying to rebuild. Groups coming together, gangs being formed, communities being created. Small, but working together well enough. Make-shift villages dot the lands.
Normal humans and animals don't do as well out in the wastes as units, due to environmental factors and contaminants. But certain areas-- thanks to units of certain powers, can be considered safer, due to group clean up efforts.
There is much unexplored, and much that many of those living inside the walls of the cities don't know about. That kind of thing.