Arifureta Shokugyou de Sekai Saikyou (WN) - Chapter 351

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.

A veteran gamer finds himself in a world similar to the game he played.You say you need to learn skills by leveling up? Sorry, I already know all of them.You say you have to meditate to level up? Sorry, I only need to fight monsters for that.

After the Calamity War, the final and most devastating conflict to decide who would claim the Divine Throne, Kael Medici stood as the last survivor.He had led armies, fought with unmatched ferocity, and performed legendary feats. Yet in the end, his fate was no different from the rest. He perished like all the others, the final casualty of the Great War, his hand just shy of the throne he so desperately desired.But when he thought it was over… his eyes snapped open.He had returned to his youth, his memories intact.The path to divinity is drenched in blood, and the battle for supremacy is merciless. Yet Kael has already endured this once. This time, failure is not an option.With the memories of his past life, dominating talent and and a mysterious power awakening within him... The preparations to reach the Divine Throne were complete.

Name: ParadoxSpecies: Snake, ?Description: A tiny snake with great potential.That was who I was. That was what I was. A tiny snake with great potential. The sole creation of the Great Core.It was just us, the Great Core and I, tucked away in our little corner of the World Dungeon. Together, we hid from the bad-things and the Coreless of the world outside - safe from the horrors that would consume us.Until, one day, the Coreless found us. Until they tried to steal away my creator. Until, with no other option, I swallowed the Great Core that had made me.Only after that did I become what I was always meant to be.At last, I became the Great Core's Paradox in more than name.[The Endless Cycle] began.Thus begins the story of a little snake zealot and his journey to greatness.