The Dramatic Crown Princess Wants to Poison Me! - Chapter 42: Shameless

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.

Freshly turned eighteen, John Newman, a helpless nerd, suddenly gets video game abilities granted to him. A mysterious higher power, a secret Abyss of magic beneath the surface of the normal world, mages, martial artists, eroticism, tragedy and a harem of hot girls awaits.

Yin Shen’s name is God.

He never thought that one day he would really become a god.

- Description from novelbuddy

The sky thunders, Fang Yue, the nail household, dies on the street, the heavenly court blackmails, obtains compensation, reincarnates, and sees how Fang Da Devil disturbs the universe and upset the world.

- Description from MTL