Nine Astra Skies - Chapter 968

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.

An alien abduction romance. Updates Mondays, Wednesdays, and Fridays.Grant has a tolerance for boredom. Late shift in a middle-of-nowhere facility? Sign him up. If the money's good, he'll happily take the peace and quiet of a long night watching an empty cell.And then he meets Subject B-31. Blue, beautiful, and completely inhuman. Her captors call her Batty, thanks to her big ears and the way she hangs upside down by her tail.He's told not to talk to her. He's told to think of her as a test subject, not a person. He's told to cash his checks and live his humble life. He's told to ignore the sorrow on her face and the desperation in her crimson eyes. Maybe he should have listened. When he finally busts her out, the rescue isn't a rescue at all: it's an abduction.Batty is Princess Sykora, of the tyrannical Taiikari Empire. She commands the Black Pike, a massive voidship on the imperial frontier. Grant must learn a new life, in a firmament filled with ambitious nobles, deadly rivals, and the sinister smiles of the Taiikari Imperial Court. And he'll have to learn fast.Because when the Princess of the Void looks at Grant, she doesn't just see a savior—she sees a husband.And she isn't asking.

I Became Hades, the God of the Underworld from Greek and Roman Mythology

The world experienced a cataclysmic change, and countless spatial gateways appeared out of thin air.