Doomsday Survival: I have a cheat

Humans had discovered a box on the moon that surpassed Earth’s civilization. When the box was opened, disaster would befall the entire Earth.

An ordinary otaku got the mysterious power from the box by chance and obtained the magical power of the built-in cheat in the game GTA5 (**).

How would he survive the apocalypse? Who was the owner of the box? What was the deadly virus in the box?