Toaru Kagaku no Railgun SS - Volume 2, Chapter 8

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.

Zhou Mu finds himself remaining in a single-player VR game despite having decided to quit after platinum-ing the entire game. However, he realizes that the world has completely changed. Realizing life in the game is better, he continues on with his in-game name, William Kane.

“Why is the world united under my name? And what’s with the religion that honors me as their god? The royals are claiming to be my descendants? Was there ever such a function in the game? What have they done for the past 1000 years when I was gone?”

Zhou Mu was completely lost.

“Are you calling me a traitor? Aren’t you guys the ones who have been doing evil deeds in my name? Behold, for you shall witness this lost forbidden spell!”

He was the hunting hound of the Baskerville family.

But at the end, he was branded as a traitor and executed.

— — —

Now, he has returned… after 40 years.

“This time, they will be my prey… and I’ll bite every single one of them to death!”

[Compatibility Level: 87%]

[Soul Transmission Successful]

[Character Creation Successful]

…

Legolas Baron, a man whose curiosity led him to pursue 3 successful careers as a zoologist, martial artist, and game producer has reincarnated in the world of the VR game that he created as a co-producer.

Unlike other reincarnators, Legolas was not intimidated by the prospect of reincarnation rather his curiosity became piqued by this phenomenon.

He wanted to know how he came to the world of the game that he co-produced. He wanted to understand the sorcery that was behind it.

To achieve his goal of getting to the bottom of how he reincarnated, he discovered that the only way to do it was to get to the peak of this game world.

Join this epic story as Legolas seeks the truth and sorcery that was behind his reincarnation by making use of his knowledge of the game to exploit invisible loopholes to establish himself as the Greatest Summoner in Dominator.

This is the story of how a man’s unshackled curiosity led him to the peak of strength as a Summoner.