The Emperor and the Knightess - Chapter 278

As a transmigrator turned extraordinary creature of the human race, he found the world to be more colorful than he had imagined.To more easily access everything this new realm had to offer, he first needed a special resume. Then, he had to find the right place in a city perennially shrouded in fog to fill out an application, and the last and most critical step...— was to kill a chicken or catch a mouse.

Hyde arrives in a doomed world with nothing but his body and fragmented knowledge of the future from a game he once played. He has no grand ambition—why try to save a world already destined to fall? Survival is enough.That is, until he discovers his sister is also transported into that world.However, only he hears the Melody of Nightingale and receives the power to survive.[You have established a connection with The Forgotten Hollow.]Awakening as a Resonant—an elite group with supernatural abilities—he is thrust into a conflict between two worlds. Armed with the authority of space and time, he vows to protect his powerless sister at all cost, even if he has to fight against the Mirage creatures, other Resonants, or even Gods themselves.

After breaking up with his girlfriend, he accidentally acquired a genius system and rose from there against the heavens, becoming invincible..

- Description from Novelupdates

This is an alternate history. Decades after the fall of the Eastern Jin Dynasty, the world is still in chaos, although there is hope for reunification.