One Piece: Madness of Regret - Chapter 39: The girl with red hair(2)

In the third year of the reign of Yu State, it rained in the city of Weizhou.

Li Ang woke up in a daze, dreaming that there was a sword hidden in his head.

- 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.

They stole his future and crippled his body. Now, he’ll rewrite the history in blood.Damon was on the verge of greatness—first in line to claim Bloodreign, the legendary artifact said to grant unmatched power in Earth Online, the world’s first fully immersive VR game. But his best friend betrayed him, stealing the item, and leaving Damon broken, crippled and nearly deleted. Kicked from the guild, mocked by the community, and trapped in a weak, crippled body, he was forgotten until his last desperate attempt somehow brought him back in time to the day when it all began.Now Damon was back and he knew what he was going after.A hidden lineage. A cursed class. A bloodline sealed since the dawn of the multiverse.Last time he played fair. Last time he trusted. This time he would hunt and devour. With years of knowledge of every exploit, every secret quest, every bugged mechanic, he will climb straight to the top. Armed with the blood of the first Vampire King, he was an apex predator now who stood at the very top.However, unbeknownst to him, a catastrophe lurks in the shadows. Damon finds out that the game itself might not be as simple as it seemed and the entire future of the humanity might depend on this game.

Six thousand years ago, Su Changsheng traveled through the fantasy world. He practiced hard and wanted to reach the peak, but he failed to even attain sainthood and was backlashed. He was disheartened, and when he wanted to die…The system was accidentally activated.‘As long as you marry a wife and have children, and develop the family, you can continue to get rewards and resources.’Su Changsheng suddenly realized the right way to advance to the peak.[You married Gu Qingge, the Empress of Destiny, and she gave birth to your first daughter. Talent: Indestructible Body, Aptitude: Peerless in the world!] [Rewards: Indestructible Body of the First Demon of All Calamities; Emperor-level Scripture!] [You vigorously developed the family and successfully promoted it to the ancient family!] [Rewards: Ancient Clan Gift Package; Luck-Golden Dragon; Imperial Weapon from Ancient Clan] [You married the Ancient Queen…] [You married Quintuplet Goddess from the Celestial Clan…]“I can have such achievements in my life, it’s all thanks to my own efforts!”Several years later, Su Changsheng, the supreme immortal master of the heavens, revered as the Great Heavenly Emperor Changsheng, humbled himself.