A Bored Lich - Chapter 309 - Incoming Storm Cloud

Qin Chen was transmigrated to the Taiyi Holy Land where he became a servant in charge of sweeping the floor. However, on his 16th birthday, he was rewarded with a system where he was rewarded whenever he signed in at a new place.

When he signed in at the Empire Ruin, he was rewarded with the strongest Chaotic Holy Body and the Chaos Emperor Scripture.

When he signed in at the Demon Sealing Land, he was rewarded with the Probationary Royal Armies.

When he signed in at the Alchemy Palace, he was rewarded with the Divine-grade Alchemy.

When he signed in at the Herb Garden, he was rewarded with an Immortality Elixir.

When he signed in at the Empire Palace, he was rewarded with the Emperor-grade Divine Art, Revival.

…

Qin Chen thought he could just spend the rest of his life signing in at different places until he became invincible.

However, when the ruin of the Great Kingdom appeared inside the holy land, people from other holy lands, prestigious families, and even ancient empires gathered to defeat the All-Powerful Demon King who appeared with the ruin. The Demon King had killed countless people and had planned to destroy the Taiyi Holy Land.

Qin Chen was left with no choice but to step up. When he killed the Demon King with a single slap, he sighed, “Why do you guys have to force a mere servant to act?”

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.

I lived my whole life as a s*ave, bound by a leash. But there was one thing that I was able to choose for myself: the place where I would die.“…Any last words?”My only friend asked me in a calm voice, and I quietly replied as I closed my eyes.“Waaaah!”…Waaaah?To cut to the chase, I was reincarnated. And not just as anyone, but as my friend’s youngest grandson. So, what am I going to do now? Well, what else can I do?“I’m going to cause chaos.”

He was the continent’s strongest and most revered alchemist, Ye Zifeng. He was under one person and above millions. However, due to an unpredictable event, he had died. After his rebirth, he had become the supertrash of the Ye family and suffered disgrace. To make matters worse, he had an argument with his fiancé that led to the break off of his engagement. In this second life, he will work to change his own destiny. He vows to return to the peak of the world, trample on those who laughed at him and rewrite his legacy!

- Description from Novelupdates