I Have the Alchemy Emperor in My Head - Chapter 2466 - : Saving People

The story begins with the last day of Yggdrasil, a popular online game which is being quietly shut down. Our protagonist Momonga decides to stay in his beloved game until the last moment, so waits for the forced logout. Unexpectedly, the server does not shut down and Momonga is stuck in a skeleton avatar in another world. “The powerful Overlord” needs now to discover the new world and face the continuous challenges that arise.

“Today’s sign-in +1 is not used, please start today’s sign-in!”

“Sign in successfully, get 10 billion cash, which has been transferred to the bank account, please check.”

Ding, 10000000.00 yuan has been credited to your bank card.

“The treasure chest has not been opened today, do you want to open the treasure chest?”

“Successfully open the treasure chest, get a luxury cruise ship worth tens of billions, a private helicopter worth tens of billions!”

Chu Ping: “This system is too awesome!”

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.