Nidome no Yuusha - Chapter 106 - Idle Talk - Far-Day Diary

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.

Encountering a car crash, the King of Silver Screen, Ye Sinian, was bound to a Cannon Fodder Counterattack System.

After reincarnating for hundreds of lives, he has finally earned enough “travel expenses” to go back home.

However, he didn’t think that the system would suddenly malfunction, making returning back home from then on hopeless.

With the shackles of a millennium broken, Ye Sinian aggressively counterattacked!

Reversing fates while hugging the mentally ill* Lord Seme, he walked towards the apex of humanity!

*Mentally ill – Schizophrenic

- Description from Novelupdates

Wen Nan accidentally gets involved in a strategy romance game. Although the game's art style is somewhat eerie, it excels in the depiction of female characters, each remarkably vivid.Wen Nan happily makes it to the end through one sweet romantic encounter after another.[Congratulations! You are the first player to pass this horror escape game!]Wen Nan sits on the throne, with fragrance in the left hand and snow-white in the right, and is stunned upon hearing the system's congratulatory words:“Huh? Horror game? Isn't this a strategy romance game?!”

Growing up in a place where the rule of the jungle is law, the simple yet cunning Shaar is thrown into the chaotic world of war and political turbulence. After a chance meeting with a mysterious young girl, his destiny is forever changed as he embarks on a journey, joining the Byzantine army and climbing its ranks. With his bizarre beauty standards, will he ever return the affection of the girls that will follow him? Will he ever learn about his real parents? What lies ahead of him is a journey of strange humor and adventure.