I created my own system - Chapter 237 Watcher

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.

Lin En transmigrated into a magical world that resembled medieval Europe but had the power of magic.Here, magic could affect and control basic particles, which was based on scientific theories that served as magic formulas!The wizards, who were actually scientists, were struggling to explore the truth of the world under the chase and blockade of the church. Lin En’s arrival sparked a renaissance of the alternate world…The white phosphorus fire, known as the Flame of Hell, the liquid nitrogen field of extreme cold, and the resonance frequency that kills without a trace… A few years later, the Holy See gathered all countries to the city, known as the legendary wizard, the pioneer of magic Lynn under the gaze of a group of wizards, wrote down the mass energy equation known as the ladder of God by later generations! Lynn looked around the crowd and said nonchalantly. “Mass and energy are interchangeable, and based on this theory, I have developed a powerful forbidden curse… It’s called — “The Big Nuke!”We will re-examine the world from the perspective of magic, where science is magic, and magic is science!

“For a long time, we humans have been like the chosen race, without any natural enemies, and have long been at the top of the food chain. Unfortunately, I have to tell you...” “When there is only one bird in a forest, then the forest is basically fake, and the bird was put there by someone...” “No matter how a fish swims, it can never meet any of its kind, which only means that the fish is kept in a fish tank...” “Yes, we are the birds in the forest and the fish in the tank.” “Yes, the world we live in is virtual!”

For Marco, Lucas is his meek little brother. For the rest of the world, he is the menacing Ghost of Vermil.“Angels endow blessings. Demons sow curses.” A hundred years ago, angels and demons descended on earth. It is said they are still here.Annointed with potent holy power, Marco is set to join the Kingdom's Holy Army to fight off the demonic legion. But before that, he must confront the trail of blood and ash that points to Lucas's involvement with the dark side.As mysteries unfold and loyalties fracture, Marco is faced with the question: where does holiness end and damnation begin? If all lines are blurred and the fate of humanity is at stake, will he have enough resolve to strike down the brother he once swore to protect?