A dull vibration shakes the sealed cockpit. Ahead, the ruins of a city, sinking into the dust, stretch toward a gray sky. The systems of the Initial General-Purpose Unit 000 power up in sequence, and targeting reticles and ammo readouts flicker onto the monitor. A single, well-worn rifle is mounted on its right arm. At that moment, an unknown signal, distinct from external comms, infiltrates the unit's interior. A warning indicator flashes red for an instant, then vanishes. In its place, a quiet woman's voice reaches your ears.

Three contacts light up at the edge of the radar. Unidentified units moving through the shadows of the ruins. Deeper still, from beneath the ground, a massive, irregular signal pulses.