My Longevity Simulation - Chapter 4: Immortal Spells and Swords

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.

Cale Virel was just a normal office worker.He was bored and tired of his life, waiting for it to end.And then—Bam!One night, two robbers targeted him!And instead of surrendering, he fought back!Though, in the middle of doing so—PHUCK!He got stabbed and died...He didn't regret it though.After all, he's not really afraid of death anymore.And so...He rested in peace..........Or so he thought!Cale Virel—“Huh? What the fuck?”He woke up as a young slave named Kaiser in a different world!And given another life he didn't ask for again—“Fuck this shit!”Cale, or should I say—Kaiser—“Ugh, whatever.”Decided to live it... By just doing whatever he feels like until he dies.

“Will you marry me, Anais?” The male lead proposed to me. “What about Selena?” “Selena doesn’t matter. You’re the only one I’m interested in now.” Even without a hint of interest in the female lead. “I’m sorry, but I…” Before I could even utter my refusal, the refreshing sound of coins rang in my ears. [asdf has donated 100 points!] Accept and get ten thousand points “Shall we go pick out a ring first?” Forget about conscience; if it’s fun, that’s all that matters.

“Beast Forge? What the hell is that?”He thought while walking out of the alley. The streets were almost empty, with only the homeless wandering around, picking up anything valuable that was dropped. He walked over to join them, still thinking he needed to do this to survive. But as he bent down, a black screen appeared in front of him, with white text displayed on it.[Beast Forge system activatedUser successfully registeredScanning user... doneUser has not awakened, cannot use Beast Forge.Analyzing for possible solutions.... doneMission: Run 10 km before 00:00Reward: Force awakeningFailure: Loss of the Beast Forge systemWill you accept this mission: YES/NO]