Swordsmeister of Rome - Chapter 18: Clash

There was once an immortal cultivator fighting for the fate of human beings. Unfortunately, he failed that time; but fortunately got another chance as he was reborn once more as a human, on the earth of 5,000 years ago. With a second chance, he not only would embark on the road of saving all mankind, but also would retrieve his human nature on the new journey that would last for 5,000 years.

- Description from Novelupdates

A man who was once called the world’s strongest agent ended up becoming a teacher after his retirement, to train a new generation of agents. After many years of training his disciples, he was killed at the age of 60 by a secret organization’s ruse and was reincarnated in another world with his memories intact. Though he was surprised by the existence of magic and the strange species in that world, he quickly adapted to his condition as a newborn and took advantage of it. He acquired special magic and gained a massive amount of strength thanks to his rigorous discipline, in order to reach his goal: Resume his career as a teacher which he left halfway through in his previous life. This is the story of a man, who, based on the memories and the experiences of his previous life, became a teacher who travels through the world with his students.

Alex was an ordinary person with the dream of one day being transmigrated to a magical world.

But what he didn't expect is that he would be transmigrated to a world much more than that, a world he knew very well, but instead of being given a system that would empower him, he was given a system that allowed him to make games, and the more people played, the more powers he would get.

Tony Stark: I hate this! I can do in real life everything this Watch Dogs guy does, but why can't I stop playing?

Hulk: HULK HATES DARK SOULS!!! HULK SMASH DARK SOUS ARRRHHHHGGG!!!

Nick Fury: If any agent can't complete the Hitman game by next week, that agent will be fired from the Shield!

A world of superheroes, but who controls everything is "only" a game developer.

A guy became a brother of Iron man and got the ability to extract genes from anyone. Lets see how he changed the Marvel World

- Description from Novelupdates