The ruins—a vast, subterranean complex where the relics of a bygone era lie dormant, shrouded in mystery.

  Beneath the tower, the ruins remain an enigma, their secrets guarded by shadows and obscured by the scant information available on the market. Why such an immense facility, capable of housing the entirety of humanity, was constructed deep underground remains an unsolved riddle—a perilous domain yet to be fully explored.

  The air is laced with toxins that rot organs from within. Grotesque, evolved creatures from beyond the tower roam its depths. Discarded experimental organisms and slaughter machines lurk in the dim twilight, ready to prey on those who seek the ruins’ treasures or the truths of the past.

  Stepping off the elevator, Danan dons a gas mask and multi-purpose goggles. The flickering lights cast uneven glows on the corridor as he grips the trigger of his assault rifle, advancing cautiously.

  The upper levels of the ruins have restored power, and the path from the elevator hall to the reactor is relatively secure. Barring an unforeseen accident—such as a new fissure allowing external toxins or creatures to infiltrate—the risk to life is lower than on the unregulated routes.

  Still, vigilance is paramount. "Relatively safe" does not mean free of danger. A crack in the wall could hide invasive critters, unnoticed until it’s too late. Hearing the faint chirping of insects from within the walls, Danan deploys the blade embedded in his mechanical arm, thrusting it into the fissure. Green slime splatters as he strikes.

  A writhing, human-sized centipede slithers out, convulsing before collapsing lifelessly. An exobiotic creature, the "Gold-Eating Centipede," feeds primarily on metal. Its razor-sharp fangs and molten acid are specialized for melting and shredding iron.

  Such creatures pose little threat. Only amateurs—third-rate scavengers at best—would fall to such vermin, practically offering themselves to the ruins’ hunger. Shaking the slime off his blade, Danan glances at a dying ruin delver, half-dissolved, and strips them of spare ammunition and rations before pressing onward.

  “…”

  Weathered corpses, fresh bodies, maggot-ridden carrion, and a figure clutching a pistol with a bullet wound in its temple—gunfire echoes through the corridor, followed by shouts and screams that fade into an unsettling silence.

  “…”

  Danan takes cover at a corner, rifle raised. He pulls out a hand mirror to peer ahead. There, a lone man crouches, drenched in blood, clutching his head.

  “No… I didn’t want this. I didn’t want to come to a place like this,” the man mutters, his voice trembling. Before him lie three corpses.

  “It’s your fault… you dragged me here, saying there was money to be made. No, no, no!” he screams.

  Suddenly, a centipede bursts from the ceiling, seizing his head in its jaws and dragging him into a crack. All that remains is a pool of blood, excrement, and a bloodstained gun.

  A falling-out among companions, driven to madness and mutual destruction—that’s the likely story. Danan knows well that teaming up invites unforeseen chaos, raising the odds of death. Ransacking the corpses for useful supplies, he slices another centipede that emerges, dispatching it with ease.

  For those lacking the ability to handle the unexpected, teamwork is a fool’s errand. Danan, who has survived as a lone ruin delver since the death of the old man who raised him, knows this better than anyone.

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  Stepping over blood puddles and leaving the bodies behind, Danan reaches a door illuminated by a green lamp. He manipulates the control panel, gaining entry to an uncharted sector.

  Where are the bodies of the ruin delvers sent ahead by Lils? More pressingly, his instincts scream of danger lurking in the dim shadows.

  The floor is slick, buzzing with the hum of flies. His boot sinks into something soft. Activating the night vision on his goggles, Danan’s gaze falls on sixteen severed limbs scattered across the floor.

  “…”

  He brushes a gloved hand over the wounds, wiping away rotting flesh. The limbs, cleanly sliced by a sharp blade, are decayed, their blood blackened.

  Yet, amidst the carnage, one body stands out: a head and torso obliterated, as if crushed by immense force or torn apart. It resembles the work of an experimental beast or a high-caliber anti-materiel rifle. But who would bring such a weapon into the ruins? No one. Danan has never seen it.

  The thought of a “Shadow Wolf,” an experimental creature, flickers in his mind. But those beasts dwell in the lower levels, not the upper strata. Still, only a Shadow Wolf, thriving in the darkness of the mid-to-lower levels, could rend an armored delver’s torso like this.

  Or perhaps this was human handiwork—a super-vibrating blade or a relic from the ruins used to slaughter rival delvers. Could it be the work of the notorious rogue leader exploring this new sector?

  Crouching and pondering won’t solve anything. Steeled for the dangers ahead, Danan advances into the silent corridor, never letting his guard falter.

  The ruins’ new sector… The upper levels have been largely stripped of relics, with exploration now focused on the mid-levels. Yet, locked sections with electronic seals remain, and when those are breached, the upper levels will once again buzz with activity.

  The upper levels are safer, relatively speaking. No creatures here can blow a head off in one strike, nor are there many slaughter machines that relentlessly pursue humans. Experimental beasts can be neutralized by destroying their heart or head. The toxins, if not too potent, require filter changes only once an hour. The true threat in the upper levels is, inevitably, other humans.

  Gunshots ring out somewhere, and further ahead, Danan finds more bodies—delvers who likely killed each other over relic shares. Among them, he spots a young girl, barely a teenager, sobbing behind cover.

  Silently, he approaches, aiming his rifle at her head. “Are you one of Lils’ hired delvers?”

  “…”

  “Answer.”

  “…Listen.”

  “What?”

  “This… this wasn’t supposed to happen! That woman never told us about those monsters! Help me, please, someone, help me…!”

  “Where are the others?”

  “Look around! They’re all dead! Killed by that man, that woman!”

  “Man? Woman? What are you talking about? What did you see? What happened here?”

  Could there have been scavengers among them, looting the dead? Scanning the bodies’ wounds and gear, Danan senses something off. If these were her companions, why is the girl unscathed? Why is she cowering and crying like a fool?

  Suspicion surges, triggering his instincts. His blade pierces the chest of a man in black body armor, who had been posing as a corpse. His mechanical arm’s blade slashes the throat of another. Blood sprays. Turning to the girl, who draws a gun, Danan slams his rifle into her, crushing her gas mask and snapping her arm.

  In the tower, in the ruins, humans are the deadliest predators. Though Danan knows little of the tower’s past or the era before, he understands this truth. Having killed countless people himself, he knows it intimately.

  Unlike exobiotic creatures, slaughter machines, or experimental beasts—whose behaviors and weaknesses can be studied and countered—humans are unpredictable. Their motives and actions demand constant consideration in battle.

  “Quiet. One more time: what happened here?”

  “Stop, please, help—”

  “What happened? Talk, or I’ll rip off your mask.”

  “I don’t know! I swear! When we got here, they were already dead! I’m sorry for attacking! Please, let me go!”

  “No.”

  “Why?!”

  “To eliminate future threats. Understand?”

  “What—”

  A short gunshot, and a red puddle forms on the ground. Kicking aside the girl’s body, her forehead pierced, Danan confirms they were scavengers.

  A staged corpse, a girl used to lure sympathy or desire, a surprise attack—such tactics might fool inexperienced delvers, swayed by fleeting compassion or greed. But Danan, hardened by countless dives into the ruins and encounters with all manner of humans, sees through such ploys. They only invite death.

  Rifling through the fresh corpses for usable tools, Danan recalls the old man who raised him: If the enemy is human, no matter how weak they seem, never let your guard down. Kill with full force, or you’ll be the one killed.

  “…”

  I won’t die. Muttering to himself, Danan steps into the vast chamber ahead, rifle still in hand.