From Human to Skeleton: Revived with Infinite System Crystals - Chapter 14: Skeletons Gambit

Henry is a university graduate who happens to be working as a hotel receptionist, though with big dreams of being more than that. All these change for good one day when he finds a way of cracking a very sophisticated technological system, which ultimately empowers him to formulate and develop leading-edge inventions from his bedroom.With a determined mind not only to conquer the market but also to move out of his gray life, Henry starts into his journey of fame by introducing a number of radical technologies that capture the interest of the whole world and hold it.

Imagine being forced to live, after death, as incorporeal bodies trapped in a vast space of nothingness for thousands of years, with nothing to do but exchanging past memories with other cohabitants (read: weirdos). Everybody wanted out, but there was no way to leave the Void…

Until one day, a young man was finally summoned, as a powerful but reluctant mentor, by a bubbly and motivated but completely naive young girl. Baiyi, finally out of the Void, was the only one who could save all of the other 32 souls from their prison and his summoner might just be The Key to their freedom.

However, Baiyi had to use the techniques and abilities the other souls had taught him throughout the years, and together with his own extensive knowledge of anime and game tropes from his shady and dangerous past as an otaku, to face the biggest challenge of them all: training the clumsy young girl he was forced to partner up with… into a competent sorcerer!

This is a story of heroic adventures, cunning strategies and romantic tales. How will our MC thrive in a world completely strange to him? Where will his ambitions and abilities take him in the palace?

- Description from Novelupdates

Lu Shang picked up a dirty teenager while discussing work at a bar. It was merely happenstance, but memories from ten years ago resurfaced when he saw the gunshot scars on the teenager’s back.

Lu Shang asked him, “What is your name?”

“Xiao Li… My surname is Li, so they all called me Xiao Li.”

“You don’t have a name?”

“I don’t remember.”

Lu Shang said, “Then I will call you Li Sui. From now on, you will be with me.”

From that day onward, a young “lover” was always by Lu Shang’s side.

Years later, Dr. Leung teased Lu Shang, “You didn’t get his heart, instead your heart caved in; boss Lu, that doesn’t seem like a bargain.”

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.