Hades, the Urban Legend - Chapter 559 - 560: Be Careful

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.

When I cleared the final chapter of a game that was a national failure, I became an unnamed side character in it.

A non-standard, unmeasurable, EX rank supporting character.

Under the vast immortal sky, the brilliance of an era is nothing but fireworks blooming at the fingertips.

Overlooking the earth, for thousands of years, life and death, where are they all? The Immortal Gate, the Dynasty, and the Supreme Holy Land are all just a handful of loess under the Immortal Vault.

A thousand years of splendor, and a smash into ashes.

Cinders sprout in the depths of the ruins, and you and I strive to be the trees that reach the sky.

What the hell is on the other side of the Immortal Firmament?

- Description from novelbuddy

“I already have a child with another man.”

It was a lie made in order to refuse the proposal of the leader of the most feared mercenary company in the entire country. But his response was unexpected.

“It doesn’t matter who the child is. Just birth it.”

She couldn’t understand.

What could this man possibly want with the princess of a failing nation?