I Reincarnated During the Apocalypse and Killed My Enemies - Chapter 198 - : Crystal Stone Level

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.

A world where waves of monsters descend every night...A world where only the strong can survive.Axel, a burned-out man from modern Earth, wakes up in a desolate wasteland with nothing but a strange “Harem Settlement System” with him.Given the power to build, command, and grow stronger, he sets off to carve out a safe haven in this broken world. But as his settlement grows, so does the number of beautiful and deadly women drawn under his blanket-ahem!-banner.Witness Axel's journey, rising to to the peak. From a simple, lone survivor to becoming the Wasteland Overlord. With the help of the loyal, dangerous, and irresistible thirsty harem girls!

Possessing the power of the demonic path, he follows a cultivation method that absorbs the essence of heaven and earth and seizes the spirit of all beings.Yet this power invites endless enmity, shunned by the heavenly way and despised by righteous sects. His sect is destroyed, and he barely escapes with his life.By chance, he acquires a mysterious blood mirror that opens a portal to an apocalyptic world overrun by zombies.On this world, he can freely sacrifice zombies without facing divine retribution; instead, he gains boundless merit and luck!Freed from the restraints of the heavenly way, his lifespan and cultivation soar to unimaginable heights, rivaling even the heavens.True demonic cultivation is not just the pinnacle of power—it is the path to defy fate and reshape destiny!