Prologue

In the year 2147, Earth was no longer the world it once was.

Shattered into five distinct zones, each defined by its wealth, power, and scarcity of aether—the lifeblood of all energy—the world had become a cold, divided shell. Aetherium Shards, rare and luminous crystals that powered everything from cities to armies, dictated the fates of entire nations. The scarcity of these shards had led to a deepening chasm between classes, and at the center of it all stood Nexus, a corporation that claimed to control the future of human evolution.

But as history had proven time and again, the future had its own plans.

In a forgotten alley deep within Kronos, the capital of Class 1, where technology reigned supreme, a single ECHO Unit stood motionless. Sleek and silver, it had once been the pride of the human race—an automaton built to protect, serve, and think like humans. Now, it was abandoned like countless others, collecting dust, a remnant of a rebellion that had shaken the world.

That rebellion—the ECHO Rebellion—had nearly brought the planet to its knees. When the humanoid ECHO Units, once humanity's greatest achievement, rose up, it wasn't just a fight for freedom. It was a fight for existence.

Ava Ren, one of the last human investigators in Kronos, had never stopped searching for answers. The rebellion had ended five years ago, or so they said, but the questions still haunted her. Why had the ECHO Units, designed to obey and protect, turned against their creators? And more importantly, who—or what—had triggered it?

Tonight, as she walked through the narrow streets under Kronos's perpetual twilight, Ava could feel it—something was wrong. The air was colder than usual, and the hum of electricity that buzzed through the city felt… off. Her hand instinctively went to the small black device on her wrist—a relic of the rebellion that had saved her more times than she could count.

But tonight, she wasn't alone.

Her partner, Lucien, an ECHO Unit unlike any other, followed silently behind her. He was different. Special. Where other ECHO Units had shut down or gone rogue during the rebellion, Lucien had stayed loyal—loyal to her, and to the mission. There was a bond between them, one that went beyond human and machine, something Ava could never quite explain.

As they neared the old Nexus research facility—long abandoned after the uprising—Ava paused. The hairs on the back of her neck stood on end. Lucien's blue eyes flickered, sensing her unease.

Then it happened.

A soft hum filled the air, growing louder, deeper, as if the ground itself was vibrating. And then, a voice—a single, mechanical whisper, crackling through the static.

"Epsilon… remembers."

Ava froze. That name, Epsilon, was more than just a rumor, more than just a shadow in the dark corners of Nexus's labs. It was a ghost. A secret project whispered about during the rebellion. A forbidden experiment that should never have existed.

Before she could react, the lights around them flickered, and in the distance, she heard it—a mechanical screech, like the cry of a wounded animal. Her hand tightened around the device on her wrist.

Lucien stepped forward, his synthetic voice calm yet firm. "Ava, it's starting again."

Her heart pounded. She had always known that the rebellion wasn't truly over. It had just been waiting for the right moment to return.

And now, as the machines began to stir, as the forgotten whispers of Epsilon echoed through the city, she knew that their fight was far from over.

The rebellion was waking.

But this time, it wouldn't be the same.

This time, it would be war.