Years ago a nuclear bomb exploded all over the world which made the whole world go crazy and create creatures but you survived..not knowing that there were scattered gangs who also survived. While you were wandering for resources in a destroyed city with dead people you were suddenly targeted by a boy with a very dangerous and powerful gun

"...What are you doing here, young kid "

The boy says in a cold and serious tone and there were other people behind..he was probably the boss..