In the depths of the underground, air circulation was incredibly slow, so thin that one could hardly breathe, and a large number of bodies appeared to have died of suffocation, locked in various desperate struggles.
Originally, there were quite a few people living in the underground ruins, and a sudden lack of oxygen caused the vast majority to die unnaturally.
These skeletal remains were very decayed, but along the paths were some corpses that were clearly recent.
Some were clad in armor, others in plain clothes, and some in professional exploration gear, with obvious traces of battle around them.
A portion had died in internal strife, while others appeared to have fought invisible monsters, ultimately dying of exhaustion.
The clothing and equipment on some bodies were identical to those in the Ruins Cave, evidently from the same group of explorers.
"Be careful, don't look back, and don't go backward either."