Unbreakable - Chapter 154 - Not expected of this

As a promise, he went out into the world as an assassin. 3 years later, after becoming the Supreme Assassin, he gave up on everything he had and returned to the ranks of ordinary people. But one day, Kismet, a mystical game created by the National Research and Development had appeared.

Enigmatic hands, spectral frame, and one cunning strike just like the swing of the Grim Reaper. The Supreme Assassin takes on the mystical world, and how his legendary tales sets off, progressively ascending the altar to becoming the best.

- Description from Novelupdates

As a lawyer back on earth, Lin Yun had never lost a case. He owed his success to three things: two blessings he received at birth (a photographic memory and the ability to comprehend anything he studies) and an indomitable will he forged himself.

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.