Fantasy

One day, a tower appeared in the skies of all the major cities…
    Humans were suddenly summoned to become “Walkers”, and they needed to clear the tower to save the world.
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    “Floor 77”
    The “Stone of regression” was discovered. Walkers could now “return” to the past. Slowly… everyone left.
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    Humanity’s last hope, “Carpe Diem” was formed, joined by people who refused to abandon the world.
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    The last Walker reached floor 100. He no longer knew what to believe.