No Game No Life - Vol 1 Chapter 1

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.

Sangyan turned into a widow known to bring misfortune to her husband. Despised by her in-laws and disdained by her own family, she volunteered to retire to a remote estate to live out her days. At this moment, she caught the eye of a tyrannical emperor with a strange illness - being near a woman caused him unbearable itching and relentless vomiting.Hence, the 26-year-old emperor had never favored any of his consorts, let alone sired any heirs. The imperial harem constantly pressured him for offspring. The common people also yearned for a royal heir. When they learned that the tyrant held affection for Sangyan, the widow with the ill-fated destiny, the entire nation opposed their union.Eventually, the entire country pleaded with Sangyan to bear children for the sickly and tyrannical emperor...Beauty widow with a deadly fate VS Emperor with allergy to women

Haewon, a violinist, is a nonchalant person who neither blocks the ones who come into his life nor holds onto those who leave. One day, his only friend, Taeshin, commits su*cide, and after failing to speak to Taeshin, who called him several times shortly before his death, Haewon is haunted by his death, even though he doesn’t have much of an attachment to human relationships. Then, he inevitably runs into Woojin, the man Taeshin had a crush on, and Haewon indifferently crumples up the business card Woojin hands him.One day, Haewon, forced into an unwanted relationship, becomes entangled in an assault case, but thanks to the business card given to him, he receives help from Woojin, who’s a prosecutor. Haewon feels uncomfortably guilty and tries to keep him at arm’s length, but Woojin is comfortable enough to take a few extra steps.

In Academy City, magic and science coexist in an unwavering power struggle. Toma Kamijo, an academically-challenged student in Academy City, wields the power of the Imagine Breaker in his right hand, which allows him to completely negate all supernatural powers – as well as his own luck. When he happens upon a mysterious nun named Index, whose mind has been implanted with the Index Librorum Prohibitorum – 103,000 ancient texts banned by the Church – Toma’s luck is about to be pushed to its limits when he finds himself in the middle of a war he never expected!