The Stunning Mad Empress: The Useless Third Miss - Chapter 29 - The Matter of the Engagement

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.

Lu Zixin has a Black Technology Chat Group of the Ten Thousand Realms , and the group members are the science and technology giants of the world.

Tony Stark : “Group owner, I will send this War Machine Mark II Armor to you!”

Red Queen : “Group owner, do you want to try the latest T virus ?”

Skynet : “Group owner, where is your world? I am going to destroy it.”

Bruce Wayne : “The Batmobile is simply used to pick up girls and today I have a great girl. Do you want to see it ?”

Vega Punk : “Recently synthesized a new demon fruit, does the group want to try an experiment ?”

Little Spidey : “I don’t care, I don’t care, do not send me the red envelope, I will retreat!”

. . .

Lu Zixin : “A group of lawless people, be careful with me!”

- Description from Novelupdates

A master assassin transmigrates into an interstellar era.

Other players were responsible for competing in the e-sports arena, while he was responsible for stringing up and beating up the other players.

His sword was hidden during the peak of day, and he was a gentleman who arrived in a flash of light;
As a vanguard of the eternal night, he was the variable between life and death in the world.

“As you know, the Star League’s difficulty levels are arranged in this way:
Paradise < Simple < Normal < Difficult < Nightmare < Hell < [Tyron Odin]”

- Description from Novelupdates

Jian Wushuang was reborn in adversity. In order to get his revenge, he began to cultivate Heavenly Creation Skill. With the help of the Heaven defying cultivation method, Jian Wushuang gradually grew into a peerless genius from an ordinary practitioner. With a sword in hand, no one is his match. Using his extraordinary Sword Principle, he killed all his opponents and eventually became number one Sword Master from time immemorial.

- Description from Novelupdates