Echoes of the Grand Hallway

A expedition group explores an underground passageways made by "previous humans". The passageway is the largest one on Earth, and no one has ever completely discovered it. They aren't the first group to explore the Grand Hallway, but the previous groups has lost signals and never came back. With the General's instructions, they must loot inside the Grand Hallway to support their fundamental needs, and report any Way-stones, or spotted locations, to the General despite the loss of signal in the passageway.