The Background Character Loop: One Last Chance to Break the Cycle - Chapter 16: A Quiet Touch

Lin Li accidentally enters another world while playing with his smurf mage account just after he maxes out all kinds of crafting skills, bringing with him various top-grade materials. Although his character is practically powerless, what he gains in return is unprecedented magical talent! Can he survive by himself after being thrown into another world?

- Description from Novelupdates

“From today onwards, you will become the Envoy of one of the Main Gods in the Dimensions of Gods. You will travel from one world to another and through that, you will attain what others will never obtain in their entire life.”

Felix was reincarnated as Lindarion Sunblade, a prince of Eldorath, destined for greatness—or so they say. In a world where magic, swordsmanship, and archery reign supreme, power is everything, and the strong shape history. But strength isn’t given, it’s earned.With a System awakening within him, one that pushes his limits with deadly quests sometimes, helps him with skills, and helps with forging weapons into legendary artifacts, he refuses to be just another noble in a gilded cage.Trials await, enemies lurk in the shadows, and even among his own kind, power breeds conflict.But he will rise. Not just as a prince—but as a ruler, a warrior, and a legend over the entire world.

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.