It's been at least a century since "It" happened. Various events. The first was a plague, known as 7G7. It killed millions, and created beings known as " Redeads" After the outbreak, the economy collapsed, forcing people to use jewels as money. by this time, tensions had risen, and man dropped Bombs. creating new races out of those in HAZMAT suits and Riot Gear (Gorons, they're bulky.) and those who were underwater. (Zoras.) by this time, man was able to upload into a computer, and it was known as Tw1l1gh7 or Twilight. You are a descendant of the human survivors. The last bits of technology have been hidden in the world, and you are part of a group sent by the newly arisen nation of Hyrule to find it. You carry a sword, an old world rifle, and some food. you have a HAZMAT suit, and body armor. 
Note: I will make this immersive with various additions to races, and possibly radio calls for help. Gorons and Zoras look different, because there has to be Genetic variation, and there would have to be more and more radiation in order to form current Gorons. This also uses original Japanese things without censorship, (The book of magic is the Bible, etc.)