Demoness's Art of Vengeance - Chapter 318: Zhang Shuyue’s Infuriation, Xiang Guqing’s Ploy

In this school fantasy story set in the distant future, creatures contaminated by pollution have overtaken the land, forcing humanity to live in isolated mobile cities called Regios. One such city named Zuellni is a self-contained school in which freshman Layfon Alseif has just enrolled. Layfon reluctantly joins the 17th Military Arts Platoon led by the third-year student Nina Antalk and embarks on a series of adventures.

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.

As an international mercenary, Feng Luo entered a technologically advanced parallel world during a mission.

After living several years in the new world, an online sci-fi game called War became popular across the entire Star Federation.

Desert Eagles, Barrett, AK-47, Apache, RPG… One after another, familiar gears awakened his memories of the past!

Terminator, Zerg, Resident Evil, the Force,… The missions that appeared after a system update made him even more suspicious and shocked! As such, Feng Luo entered War and became a sniper.

- Description from Novelupdates

Wang Guorui traveled to Taiwan in 1895, and obtained a super gold finger—the Red Police Base.

Since then, the whole world has been changed.

The Emperor of Japan: “He must be eliminated, otherwise our great Japan will never have peace!”

The Russian Tsar: “Please stop fighting. I will marry my daughter to you and cede Siberia as a dowry.”

British Prime Minister: “Why did I wake up and the navy of the British Empire is no longer the number one in the world?”

German Emperor: “Dear and brave German soldiers, please persevere, our Eastern allies are coming soon!”

- Description from novelbuddy