5. Weather
Nothing complicated and nothing doing. Nothing would set the mood better than a little acid rain and nuclear ash falling from the sky. The Fallout worlds were often accused of being a bit bland. Well duh, they take place in a burnt out, nuked desert. But one way to spice up life a bit would be to add a bit of dynamics to the weather situation. That might not work in modern day deserts, but who's to know how weather would be different after a nuclear war?