THE GOD EATER - Chapter 43: Power Outout.

This is an alternate history. Decades after the fall of the Eastern Jin Dynasty, the world is still in chaos, although there is hope for reunification.

In a world where everyone changes jobs, I actually awakened to a unique dual career.

And a life-defying career?

High-quality items to cherish? I synthesize directly.

Cherish high-quality skills? I synthesize directly.

Senior pet cherish? I continue to synthesize, wait, how did this beast girl become so big after synthesis?

Let’s start with the synthesis of three skeleton summoning books…

Synthesis – [Undead Army]

Three more dark staffs to synthesize…

Synthesis – [Death Scepter]

The game competition of billions of races in the universe, our solar system, can we earthlings stand on a broader stage!

…

- Description from novelbuddy

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.

“Ding! Soulbinding has been successfully completed; you will now head to the Heaven Awaken World.” After hearing this, Zhao Fu’s vision darkened as he fell to the ground.

With bleak prospects in the real world, Zhao Fu’s life is turned around when countless crystals fell from the sky one night, which people could use to enter an alternate, game-like world. After obtaining an ancient Chinese empire’s legacy, Zhao Fu uses his intellect and resourcefulness to develop his own empire from a tiny village. However, with enemies both in the real world and in the Heaven Awaken World, he must make brilliant decisions and use creative schemes to survive.

- Description from Novelupdates