Reaper's Purgatory - Chapter 15: Untapped Potential

The first great emperor in the world was betrayed by his confidante and perished. Millions of years later, the great emperor’s soul returned and was reborn as Ye Yan, the son-in-law who was kicked out by the Chu family with a letter of divorce, restarting the supreme journey. Open the gate of immortality, kill the Jiuzhongtian, and cast an invincible name again!

- Description from novelbuddy

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.

Blue sky, white clouds, lazily lying on the beach, while feeling the gentle breeze coming from the sea. Hounds at the side with marine animals chasing each other around. Cups of unrivaled wine from his personal winery with cuts of prime A grade steaks readily around. For others, life is all about pursuing money, power, and fame, but for Jiang Hai, this type of lifestyle is what he constantly dreamed of.

- Description from Novelupdates

The story begins with the last day of Yggdrasil, a popular online game which is being quietly shut down. Our protagonist Momonga decides to stay in his beloved game until the last moment, so waits for the forced logout. Unexpectedly, the server does not shut down and Momonga is stuck in a skeleton avatar in another world. “The powerful Overlord” needs now to discover the new world and face the continuous challenges that arise.