End of the world

A small country, which was separated from the former empire, inhabited by kind, naive people, isolated itself from the aggressive world, closing the border. It is called the planet of children of the sun. Its inhabitants relate to enemies, like a peasant, good -naturedly cutting a pig.
The heroes of the story living in this country, representatives of the former title nation of the empire, were in mortal danger.
Universal ignorance leads to a global catastrophe on Earth flying to Tartarara along with people and states. The death of everything is inevitable! People, although belatedly, begin to realize: in order to survive, it was necessary to protect their planet.
And no one except aliens can help them