My Lycan Mate of Suicide Forest - Chapter 61 - Stay With Me

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.

After announcing it will be discontinuing all service, the internet game ‘Yggdrasil’ shut down… That was the plan, but for some reason, the player character did not log out some time after the server was closed. NPCs start to become sentient. A normal youth who loves gaming in the real world seemed to have been transported into an alternate world along with his guild, becoming the strongest mage with the appearance of a skeleton, Momonga. He leads his guild ‘Ainz Ooal Gown’ towards an unprecedented legendary fantasy adventure!

Yun Woo is the youngest author in history to enter the literature world. His debut work was a massive hit but this success was short lived for the unprepared.

A Hentai World is a Dangerous Place, Especially if Your Best Friend is a Hentai Protagonist and You Are a Trap.