Infinite Leveling- The Only Player

What would you do when the world suddenly changes?
Monsters appeared, Human Weapons didn't work, Animals started mutating and the only way for humans to survive was through constant battle.
Whether it was a coincidence or just pure luck, Alan became the only player in the entire world. Only he could access the virtual world where he could grow through killing monsters and finishing quests.
But, the problem he will face might be more than just that. When the population of entire earth collapses with billions of people dying in a single day, somebody must step up and protect the remaining people.
Enjoy the journey of a hero, a leader, and the only Player who could limitlessly level up.
This is a story about a lucky man who became the The Only Player.