Reincarnated with a Country Creation System - Chapter 159 The Aftermath in Ruthenia

[Harem + Light System + Mystery + Eerie world]After being transported to an unknown realm, Huang Ye unexpectedly obtained a martial arts manual—the Jade Maiden Heart Sutra, a technique meant for women.With no other choice, he followed the concept of opposing yin and yang, practicing the technique in reverse.By accident, he mastered a form of Dual Cultivation. From then on…

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.

The world was once at war with 10 alternate worlds. This was known as the Concept War and our world won 60 years ago. All of this was concealed so no normal people are aware of this fact in the current time.

After the death of his grandfather, the high-school student Sayama Mikoto is suddenly summoned by the giant corporation IAI. He learns this world is headed for destruction due to the acceleration of the Minus Concepts. To prevent this, negotiations must be undertaken with the survivors of the other parallel worlds so their 10 concepts can be released.

And so Sayama is caught up in the final battle to clean up after the Concept War which left behind so much enmity.

This was the great era of vast warships and the Star River, a time when the multi-universe was shattered and countless Cosmic Fragments were scattered across the void, forming the boundless Shattered Starry Sea.Immortal Domain Dao soldiers, mechanical gods, golden giants, wizard Dominators…An endless array of strange civilizations.Starry Sea Oddity, Genetic Potions, exoskeletal armors, Floating Land Origin…Treasures that could be found everywhere.Spectral Shuttle, Spectral Airship, Spectral Warship, Escort Ships, Battleships, Star-Annihilating Starships, hyperdimensional mother ships…The clearly stratified Xinhuo warships.Song Chi held a Zhu Tian Ruins Market in his hand and engaged in interstellar trade with the countless peoples of the Starry Sea.What? Titanium Crystals are worthless in your Star Domain? I’ll take them all, damn it, this is a strategic resource!You call this a chunk of iron? This is Mixed Elemental Copper, the ultimate Enhancement resource!Ordinary ship cannon? Isn’t this a golden Star-Annihilating Cannon? Quick… I’ll buy it!…Stretching across the stars, starting from the flame of human civilization.