The Call of The Tree
One day, 15 years ago, the people started waking up inside a colossal pit, which walls are covered by the buildings from different ages. Suspended in the middle of the pit, there was a giant seed giving off the light.
Soon people discovered that they cannot leave the pit, as the moment they go to the surface, their bodies crumble to dust. They also couldn't reach the seed as some invisible force was stopping them.
Explorers found crystals inside the ruins of the pit that could be used as sources of energy and many weird artifacts.
Different fractions were created, each having different goals and purposes.
The Pit is filled with many dangers and anomalies bending the rules of reality.
The characters wake up. The same day everyone has the dream of motherly voice calling to them.