Cohabitation with Sword Spirit - Chapter 245 - 206: External Object

Liu Yan, an ordinary office worker from Earth, unexpectedly traveled to a strange world.

The heroes of the ages are on the side, embarking on a journey to conquer the heavens.

- Description from novelbuddy

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.

In the novels, all kinds supporting male leads are not only handsome but also talented. However, the existence of the female lead’s halo makes them lose their lives and properties!

In order to change this situation, male supporting role rescue plan officially starts.Gu Jinmi was inadvertently selected by the system. However, for her own happy future, she will work hard.

(There’s another novel with the same name but different author. The story is different too.)

- Description from Novelupdates

Author : Yi Shi Si Zhou 一十四洲“Until the day humanity falls.”In the year 2020, Earth’s magnetic poles disappeared and humankind was nearly wiped out by cosmic radiation. Within the span of a hundred years, living creatures began to mutate and devour each other while the remaining humans, numbering in the tens of thousands, struggled bitterly in their man-made bases.In the Abyss, home to the mutated xenogenics, there lived a sentient little mushroom. Because it had been nourished by the blood and flesh of the deceased human An Ze, not only did it take on a similar-looking human form, but a similar name as well: An Zhe.An Zhe is determined to go to the human base to search for his spore, which had been harvested by humans. Once there, however, he faces the omnipresent risk of discovery and certain death as he tries to keep his non-human nature hidden from the Judges, whose responsibility is to inspect for and eliminate xenogenics like himself. And of all the Judges, Colonel Lu Feng is the most perceptive and merciless—as soon as he determines that someone is a xenogenic, he will execute that person on the spot.But An Zhe’s mutation goes undetected by Lu Feng’s eyes, and so a tale of humans and xenogenics unfolds…