Who Let Him Play Yu-Gi-Oh! - Chapter 104: Dueling Can Kill

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.

Zhang Xuan, one of the most shameless MCs in Webnovel history, enters the [Source World], a plane higher than the Firmament. With the complete Heaven’s Path Library that contains the abilities of Heavenly Flaws, Heavenly Order, and Heavenly Nature, he embarks on a journey to dominate the world.Seeking fate, recognizing fate, understanding fate, establishing fate… While you all are still refining fate, finding fate, and borrowing fate, I, Zhang Xuan, possess eternal destiny!(A novel full of face-slapping moments. Even if you haven’t read “Library of Heaven’s Path,” you can enjoy this without reading barriers.)

“Please... give me a baby.”His eyes cut like sharp blades: “Even if it's with your husband's own brother?”I nod, trembling.To save my dying husband, I would cross any line.What started as a deal spun out of control in the darkness.“Look at me,” he grips my chin. “What are you craving?”I shake my head, biting my lip as tears fall.“You want this...” his lips brush mine, “you want me.”

He died on the wedding of the girl he had a crush on, after a long and successful career. After convincing Yama to send him back to the world, he decides to fix the areas in which his life went wrong. Realizing the lack of love and romance in his past life, he sets out to conquer the hearts of various women.

- Description from Novelupdates