All of the stories begin with this endless resets, you woke up in this room again and again, select the gears you need and opens the door. Enter those scene that happened over and over, combat then death. With these memories, another reset. You wake up.
You begin to understand this is a trial, your capability is constantly being provoked. With every reset, live as far as possible, understand as much as you can. The pieces of memory will show you the truth of this endless trial. During the game you will walk among the gigantic artificial city, bloody battlefield, ancient ruins. They are full of danger, waiting to be challenged. Only by getting stronger you can understand the ultimate purpose of this trial.