MTL - I Made Scientific Magic - Chapter 398 Experiment with nuclear magic!

After 2000 years has passed, the ruthless demon lord has just been reincarnated! But his aptitude at an academy for nurturing candidates for demon lords is, “Inept”!?

A decision can destroy the sun, moon and stars. A finger can kill the Heavenly Overlord. While chatting, the Heaven and ten worlds can be annihilated.

A poor little kid walks out from a remote mountain area while holding the Nine Dragons and the Incredible Cauldron. With a control over the time and space eternally, he embarks on the Path to God where he defies the odds of the boundless universe gaudily by fighting against royalty and clashing with the legendary generation.

- Description from Novelupdates

Luo Zheng is at the bottom of the Luo Clan hierarchy, despite his family being the founders of a power refining technique that could instantly defeat any opponent.

One night, enraged by unfair treatment from a family steward, Luo Zheng burns the family records. In doing so, the hidden magic in the book engulfs him and Luo Zheng becomes a new skilled fighter. Fleeing his home and despicable clan, Luo Zheng must learn to harness his powers to rescue his younger sister while his own cousins are on his pursuit.

- Description from Novelupdates

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.