Hades, the Urban Legend - Chapter 616 - 619: Dumbfounded

Kael was a “rat”—a lowly stable boy in a frozen, brutal medieval world where Knights ruled with iron and Barbarians crushed skulls with bone clubs. His life was worth less than the manure he shoveled. That changed the night he butchered a Knight with a rusty dagger to pay a debt of blood.Chosen by the God of Slaughter, Kael awakens the Aether System. His cheat? The ability to project his soul into other worlds, live countless lives, and bring their powers back to reality—if he survives.But power is not free. It is bought with pain, time, and sanity.World 1: The Wild West. He spends a lifetime as “El Lobo,” a legendary gunslinger. He returns with the muscle memory of a master marksman and a 12-gauge shotgun. World 2: The Martial Arts Realm. He trains for decades as a Wuxia disciple. He returns with internal energy that can shatter steel.Now, as the Kingdom faces war and monsters surge from the dark, the nobles sneer at the servant boy holding a strange metal tube. They chant spells. They draw enchanted swords. Kael takes a slow breath. He racks the slide. Click-clack. “Parry this.”

A scientific genius named Thomas Harrier was transmigrated to an imperial prince body after a car accident that took his life. He found out that he is in a world similar to our own with a timeline akin to early twentieth century. The body that he is occupying was the imperial prince of a failing empire who suddenly rose to power after a successful assassination attempt of his father. Unaware that the attack is just the beginning of what is to come. He faces many challenges throughout. Will Thomas Harrier be able to live his second life in peace while running an empire and getting it back to its former glory? Or will he succumb into a conspiracy lurking within the country's borders?

Expect some:

Cold war era techs.

Super battleship with advanced electronics, propulsion, and fire control systems?
Helicopters?
Missiles?
Modern medicines and equipment?
AC-130?
A nuke?
Challenger or Abrams or Leopard?
F-4 Phantom or MIG-21?
Colored TV's.

Everything!!!

PS. Cover not mine, I just found it on google.

Fanatic virtual gamers:
Tired of the stereotyped linear drama emotions? Want to try a real open world game?
Are you tired of playing an RPG that can only play a role? Want to lead the subordinates in virtual reality and experience the thrill of governing the army?
Welcome to the massive open killing game “War in Heaven”.
……
Seeing the game’s winning and losing judgment mechanism, a professional player who is interested in PVP for 20 years and is also very interested in AI, has a bright smile:
“It’s time to show the real killing method… How about building an AI army by the way?”

- Description from Uukanshu translation

What would happen if someday, someone gave humans the opportunity to have the power of the legends?Total Chaos!That's the answer to that, people started killing, r*ping, extorting and torturing, to become the strongest.In such a world, a nerd like Eric became one of the strongest.With the resolve of a better life for his family, his loved ones, he managed to flip his destiny around, and become the strongest, and built his Empire.He went so far, that he was close to ascending to the Immortal World, that world of dreams.His story looks like one of a fairytale, but a fairytale it's not.Just as he was about to ascend, he was betrayed and killed, by his closest friends, and his half-brother.At the death's door, he learned about his brother's atrocities, but his time had finished.If only he had another chance!If only he could have another shot at life!He would definitely live differently!But could he!?At that moment his soul was transferred into a black space!