The Synthesis Wizard - Chapter 142 - : Uninterested in the Tower of Stars?

He—an enigmatic and cold-blooded soldier with a mysterious background.
She—a ruthless and bloodthirsty spy.

Emperor Gabela: Imperial legions are unstoppable on land.

Great Orc Chief: All the warriors of the tribe can count as ten.

Jade Realm Elf King: The forest ranger has never missed a shot.

Chairman of the Horn Bay Alliance: The alliance fleet is the undisputed ruler of the sea.

A mysterious organization: The prophesied era will finally come.

Paul Grayman: I am not targeting anyone. Everyone here is rubbish.

Start the journey of guns and cannons crushing the low-magic plane…

(This is an old-fashioned story about climbing a technological tree in another world to farm for hegemony. The author has limited knowledge and may make some mistakes in technical details. Criticism and corrections are welcome)

- Description from novelbuddy

[Nakseong High School, the heads of 300 people exploded!] Lee Joon, an ordinary high school student.During the entrance ceremony, he was caught up in a strange phenomenon and died.[You have died.] [Restarting from checkpoint.] [Loading…] And then a message appeared before his eyes.『Welcome to Nakseong High School that is full of mysteries and secrets.Uncover the dark secrets hidden around the school, or fight against urban legends and myths to earn points and unlock special abilities.Then, gather companions and stop the resurrection of the demon king before you graduate.The world is in your hands.』

In a world where dungeons were an essential part of it, Rein was trying to conquer as many as possible. They were the key to gain powers in the fastest possible way. So, to reach his full potential and to become the strongest, he became a great dungeon conqueror.With his trusty friends and lovers, he was definitely going to reach the peak alongside everyone. Join Rein and see how he went from strong to stronger and then the strongest.__________________1. The harem would not be too large(I'm not sure how many but probably just 4-5 main and few other here and there). All the girls would be getting their time and story.2. The story is starting when the MC is in the middle of his growth stage and not at the very beginning. But his beginning will be mentioned in the story in some form.3. I don't think I need to mention this, but obviously it will not have any NTR, rape or that kind of stuff. It is actually quite a wholesome story focusing mainly on adventure, action and bit of romance and slice of life.