Penumbra (video game series)/Headscratchers

• What was the deal with the giant worms? Were they mutated by the Tuurngait? Why?
• Why did any of the people trapped in the mine area just stack a bunch of boxes and reach that hatch that Phillip entered through?
• Who knocked out Phillip at the end of Overture?
• What's going on in Requiem? If it is in Phillip's imagination, why is he imagining all of that? If it is real, why does the Archaic have all these facilities?