Okay so the story takes place up in the northern hemisphere around glaciers and polar bears and all that good stuff, its main character is named Xavior and he is a good human adapted to the radioactive polar environment. Before the war and all of this happened genetic engineering was booming and some people made a controversial move towards editing their genomes to make them more specialized.
Xavior's genetic altering consists of having a slow-growing thick exoskeleton-like armor around his body to protect him against radiation and wildlife; it is very hard to break. He also has a very good immune system a lot like that of bats, a fast metabolism because he cannot store much fat from his shell restrictions, high iodine levels, and a very good set if kidneys to get rid of almost all his bodily impurities so he doesn't need to sweat them out. He is born with highly developed muscles so he can move around with his exoskeleton and the exoskeleton can take a lot of damage, even machine gun fire.
He has a pet woolly mammoth because in the past they were revived through cloning and some were put in the while others were trained to use to make money for the extinct animal revival program. His mammoth looks a lot like a giant baby mammoth and helps raise morale and carries his supplies for him as he travels around.
From all the radiation most of the survivors have mutated and the fertile ones bred; the most beneficial mutations became common so the humans look a bit weirder. Things are much simpler now and reflect the early Dark Ages. The people look back at the ancient society like a Utopia and feel bad about where they are now, and to remove that depression they feed their reindeer mushrooms then drink the urine as a drug.
They eat a lot of meat and bread and any other food they can find up north, in particular, they love their salmon. It's really cloudy and cold as the average lowest is 0F and the average highest is 57F. Most of the people work in a feudal-like system with a lot of reindeer farming
Xavior is a merchant who goes to the wrecked old cities and brings back these items from them as relics and sells them for food and other supplies. He scavenges for food leftovers and eats a lot of honey.
So does this seem like a sound post-apocalyptic setting or is it inaccurate and needs work?