Nobody's too sure how or why. All they know is that mechanical monsters attacked everywhere and at once. Only one name was ever mentioned: X.A.N.A. Where it came from or what it wanted was unknown. All humanity knew was that they eye brought only death.

Within days, the world was overrun. Earth's military forces were decimated and most large cities were destroyed. The humans who managed to survive the onslaught fled to ever more withdrawn and isolated parts of the planet hoping to escape the never ending armies of machines.

The death toll mounted. Humanity fell further and further back.

With it came codes and instructions. It took 5 years for what remained of humanity's greatest minds to decode and make sense of them. They spent the next 2 following them. By the end of it, they found themselves with a way to send themselves to a digital world. One where they could fight X.A.N.A. For the first time, humanity could defend itself.

Whilst they are unable to reach Lyoko itself and therefore shut down X.A.N.A.'s main control over his armies and servants. The various groups of Lyoko Warriors scattered across the globe can travel to their local Replika. A few select individuals would even receive a series of codes, seemingly randomly but ones which proved invaluable as they allowed those who carried them to deactivate the red towers. By deactivating a tower on their replica, they can halt any X.A.N.A. attacks in their immediate vicinity.

Since then, the war has come to a stalemate. X.A.N.A. struggles to eradicate the last pockets of resistance whilst they are unable to push back the machines any further than they already have. Meanwhile, cities under the artificial intelligence's control have popped up all across the world. Bringing with them a new threat: humans loyal to X.A.N.A.