The Savior is just a 3-Year-Old - Chapter 1562

(Female disguised as a man) Accidentally transmigrating into Long Aotian’s male novels is not scary, what is scary is transmigrating into a villainous little boss who will be tortured and killed by the male lead! ! Jiang Ru decided to cling to the male lead and change his fate. However, the hero is too sick and delicate, what should she do if she still feels that she can’t survive? ! Of course, thirty-six strategies are the best way to escape! Jiang Rudong hid in Tibet, fearing that the male protagonist would take him back and execute him Ling Chi, but on the way he heard that this sick and delicate king had a white moonlight who loved him to death… Hey, wait! Why is this Bai Yueguang… the same name as her? ! ! ! One day later, Jiang Ru realized that those who came out to mess around… always had to pay off their debts with their own bodies.

- 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.

In his past life, Ethan Steele was an ordinary man living in a modern world—working a dead-end job, struggling through the monotony of daily life, and haunted by regrets of missed opportunities.At the age of 23, his life came to a sudden, unexpected end in a car accident. As his consciousness faded into darkness, he was sure it was over.But fate had other plans. In the divine realm, the God of Fate watched over the balance of life and death.Ethan's untimely death was a mistake, an anomaly that diverged from the preordained path of his destiny. It wasn't yet his time to die, and so, the god decided to give him another chance.“You were meant for greater things, Ethan Steele,” the god's voice boomed. “To correct this error, I will reincarnate you in another world—one filled with magic, swords, kingdoms, and adventure. You shall be reborn, but you will not remember your past until the appointed time. There is, however, a... complication.”By divine error, the god accidentally bestowed Ethan with the Harem God System without having any idea about it.This system is a powerful, reality-bending system that would allow him to charm and seduce influential women to build his harem, growing in strength and power with each conquest.“Your memories of Earth will return on your seventh birthday. I hope you enjoy your life here in this world”And with that, Ethan's soul was transported to a new world.

Lin Xiao, who just won China’s first World trophy, got in an accident and was reborn five years later.

With the rapid development of the eSports industry, the career as professional player bloomed, the Club’s Gods circle/Professional Commentators circle/Popular MCs circle, the old friends from back then were all over the place.

The return of a King, aiming for the League, going from an unknown rookie to once again rising to the top.

Reporter: Regarding the rumours between you and Captain You, is there anything you want to say?
Lin Xiao: With all due respect, with my ability there is no need for un-spoken-rules!
Reporter: Captain You, is there anything you want to add?
You Jing: The rumours are true, back then he was vying for my love.
Lin Xiao: …how many times do I need to say it, that person wasn’t me!

- Description from Novelupdates