Post-Apocalyptic System

One day, a seemingly ordinary man in his mid-twenties was on his way to work when all of a sudden, a mysterious and violent shaking of the ground happened around the world before being transported into an unknown place with every single human being on the planet. All of them were confused of the mysterious phenomenon that happened until a voice spoke out to them out of nowhere and identified theirself as "God." This so-called "God" explained to them what happened to all of humanity, and explained to them about being in series of trials wherein they get to sit at the Elysium of Earth once they reach the end of trials. Little did they know, everything on their planet was going downhill in an instant. A trial where people are required to pass by killing each other where failure means death and the Earth, now being ravaged by monsters. One of the biggest keys to survival in this new world where violence sits on top is, selfishness, greediness, sacrificing one's good conscience, and having the will to get their hands stained by blood to get the power you need to survive. In this new world, how will humanity adapt to this situation? Are they willing to continue existing? Will humanity itself be extinct all because of monsters? Once the trials have finished, is it going to go back to what it was before? Or is beyond this hell of a world another hell? "If we were chess pieces, she was the Queen and I was the Bishop. Most would think you are the King, but you are none of us. You're nothing but the player itself." - Gang Chaewon to ??