President's Contract Wife - Chapter 42

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.

The story is about a a hitman, Who dies because of his own recklessness and transmigrates into a game he used to play after his retirement as a hitman.I'm not gonna spoil any further, but i might answer few of your questions.Is MC overpowered?Nope, he'll become strong over time and all battle he'll fight will be because of his effort and techniques.Is there magic and adventure?Yes! It have both magic like normal isekai with adventure and fighting with monsters and many other things. There are other important things like “Essence Stone” But let's talk about it in the chapters.There will be harem?Not really, He will be in contact with many beautiful female and males but one waifu but i haven't decided yet.All i can say is, give it a try, I'll try my best to make it worth your time.

“I can’t do it anymore. Stop it…I can’t take it anymore!” The second young master stopped in his tracks and raised his brows as he stared at Miss Jiang. “All you had to do was jog, so—”

Everyone knew that Miss Jiang was an artiste who had been defamed and blacklisted before she became famous again. When she got into trouble, she did not give up but fought persistently. Everyone knew that the second young master was the mysterious head of the enterprise. He was an extremely cold person with an exquisite taste. Moreover, the second young master had recently adopted a new hobby. He took in his younger brother’s ex-fiancée and he was extremely fond of her…

- Description from Novelupdates

Cultivation is about refining oneself and one's heart.The heavens and earth are the furnace, creation is the work, yin and yang are the carbon, the myriad paths are the copper, and with a steadfast Dao heart, one can refine a Primordial Dao Fruit.Refining pills, refining tools, refining formations, refining talismans, refining swords, refining souls, refining medicine, refining plagues, refining demons, refining devils, refining the heart, refining worlds, refining the Dao...Everything in nature can be refined!This is what Xuan Qing says.If you provoke him, he will even refine the Heavenly Dao to show you!Of course, this all began the day he joined the Jie sect...