I have a couple questions which I would like answered.

[Kedjane]

The Tech Demo had the Shelter setting because it was their original idea.
This was changed due to the series becoming a trilogy and the player simply stumbling upon the Shelter randomly and then spending three games worth of time in it simply didn't add up. So instead they let Overture Ep. 1 be sort of a prelude to Overture Ep. 2-3, giving a bit more story about how Philip found the Shelter. Then when the trilogy was replaced with just one sequel they squeezed together the story line of Ep. 2-3 into Black Plague.
So originally the Shelter was supposed to be a lot longer, instead the mine got about half of the story.

In the Tech Demo the screen probably goes red due to some supernatural attack, or a virus, but it's quite possible that they hadn't thought of the virus idea yet.

This is what I think, anyways.