F-Rank Soul Eater - Chapter 118: The Wheels Move Round.

A world-famous hacker and daughter of the most powerful criminal family who ruled the international underworld for many generations is killed when their organization is annihilated in a single night.

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.

As a successful author, Max was used to hate comments but he never expected that his decision to kill an important character would result in his death.Apparently, the Goddess and her brother used to read his novels and were both a big fan of his works. Sadly, the brother didn't like his decision and killed him.As compensation, the goddess decided to send Max in his own novel as the protagonist and complete the story without letting any of the main characters die.Max had no problem with that, so he accepted it and asked for something else too.“Can I court you?”Now, he has the Goddess accompanying him as the Ultimate Leveling System. Not only that, his system also rewards if he saved the favourite characters of his novel. What could be better than this life?[You have Killed the Giant Behemoth Dragon, granted 200000 EXP.][You have saved the side character, Charlotte Sinclair, granted the fortune worth Corelhelm Kingdom.]Watch as how the author makes the harem of his favourite characters while leveling Endlessly....What to expect-Leveling+Mana Cultivation+Labyrinth adventures-OP MC-Light Hearted, Low stakes-A proper Harem and good romance-Very less Smut (yeah, the number of those chapters will be very low as I intend to focus on relationships, adventures and of course Labyrinth stuff.

Yang Feng somehow transmigrated into a different world and received a legacy of an ‘ancient high tech’ family, which does not directly raise his power, but gives him the technology to build things which are way more advanced than the seemingly medieval world.