MTL - After the Divorce, the Boss Dressed As My Dog - ~ Work related

The mysterious boy Ling Chen is saved by a little girl as he lay on the street dying. Years later, he strikes a deal to save this savior-turned sister and enters the virtual world. In a future Earth where advanced warfare has forced nations to settle issues virtually or else suffer the consequences, Ling Chen bursts into the scene and goes from unknown to legend. Yet all is not as it seems, for Ling Chen has a dark past, and there is a greater mystery at hand behind this virtual world.

To save his terminally ill little sister, Ling Chen enters the newly released virtual game world and joins a small gaming studio comprising entirely of women. From now on walking upon his path towards the pinnacle. An ancient, evil item almost forgotten by history, the “Lunar Scourge” helps forge his unsurpassable legend, and causes him to unknowingly step upon a path that is destined to be punished by the heavens, the way of the Shura.

- Description from Novelupdates

Every twenty years, the world of Tower Defense arrives to take away people and make them participate in the survival game. You can get unimaginable rewards if you can win. You can also inflict severe damage to your country if you lose.

Pierce finds himself in this world, and sent to the Tower Defense alone, while other teams have a hundred people.

Fortunately, he awakens golden hint system. Not only can he see useful alerts, he can also discover the fatal weaknesses of his enemies. Every monster he takes down rewards him with top-tier prizes. While the other players are still struggling, he is already swinging his swords to take the lives of gods.

Levi, a young man who spent over a thousand years in a cultivation world, awakens in a hospital only to discover that two years have passed on Earth. The world he left behind has completely changed—mysterious spiritual energy has appeared, transforming Earth into a cultivation world filled with monsters, undead cultivators, and mysterious places like floating islands.Though Levi is furious that the entity who transported him to the other world failed to stop time on Earth as promised, he must now face the new reality. In a world now filled with cultivators, interdimensional conflicts, and the presence of a cultivation leveling system, Levi struggles to adjust to his weakened human body while seeking to uncover what happened to his mysteriously missing family.

The world that nurtured the civilization which reached the pinnacle of magic was on the verge of destruction.
The last survivor transmigrated to the past, when the magic civilization started growing, as countless mages were still fumbling their ways through the thorny paths of magic knowledge.
He, who came from the end of the magic era, aim to reach the pinnacle of magic.

- Description from Novelupdates