The Fatebound Monarch - Chapter 64: Mourning Veil

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.

No family, no power, no inheritance — a thrice-lacking protagonist. Just how will the seed rise up from the mud?

- Description from Novelupdates

She was bored, so the Emperor accompanied her as she played in the three thousand realms and caught a phoenix for her to sit on. When she has cravings, the Emperor crossed through space to gather all kinds of delicacies and immortal fruits for her. Later on, she liked little kids, the Emperor tricked her, saying if she becomes the Empress, she’ll get her own kid. And like that, she became the Empress and got tricked by the Emperor into bed. However, she reincarnated and forgot everything…..

- Description from Novelupdates

“What’s my class?”[Beast Tamer – Class E]“..Seriously?”Lee Min-Jae was a workaholic with no social life who died slumped over his keyboard. When he opened his eyes, he was in an RPG-like world — but with the worst class imaginable: Tamer.Tamers were seen as useless. Weak. Limited to disloyal, expensive-to-keep wild monsters.But he wasn’t just any fool. He was a systems-obsessed gamer, an expert at finding exploits and shortcuts.With his cold, analytical mind, he chose to break the game’s rules — by leveraging the most reviled mechanic of all: contracts.Where others saw abomination, he saw an exploit. And he was ready to turn the worst class into something unbeatable.---------------This story have:[Adventure][Smut][MSmut] (no NTR).[Harem][System / LitRPG][Strategy] - cold planning, exploiting mechanics, creative use of abilities.[Cold and Calculating Protagonist] – no naive romance.[Worldbuildin] – rules, politics, economy.[No NTR] – the protagonist is not betrayed, no passive humiliation content.