AN ADVENTURE OF AN NPC(Book 1 "Side Characters's Mission")

Behold! A new genre is coming: The stories of the technological downgrade.
In the year 2041, an all-powerful alien civilization punished humankind for breaking Galactic Union law with a "downgrade." Human civilization was reset to the technological level of 1939, for a reason they never explained.
"We live on a retro-Earth, technologically speaking. We ride vintage cars, fly vintage planes, work in vintage factories with vintage machines, and die from diseases that weren't curable back in 1939. And the damn Aliens, called the First Ones, never bothered to explain to Earthlings why they had been punished. Why? Because it's a part of the atonement to find out for ourselves!"
This story follows Timm Thaler. His adoptive father from Japan named him after the protagonist of a well-known fantasy book and trained him for one single purpose: to solve this mystery and get human civilization progressing again. He is meant to break the chains that have held humanity back for two hundred years, locked in an endless 1939. But now his father has passed away, and Timm stands in a cemetery looking at his grave.
On a distant planet, the mystery begins to unravel. The aliens have recreated a world from a famous human virtual game, populating it with the game's once-digital characters. They have given these synthetic beings-created by humans for entertainment-free will and real lives in the physical world.
Despite his immense hatred for the aliens, who were responsible for the death of his parents as consequences of the regression, Timm Thaler agrees to take on a mission that might finally reveal the truth.