I'm a little disappointed that we don't get to see the classic flying saucers that were pictured in the first chapters, but the cool design of the aliens makes up for it.
While I was wrong about which natural enemy they would summon on such short notice, the "don't pray!" warning by the Mad God World woman suggests it may still happen to deal with the aliens later.
"All living things", huh. That opens the possibility that demons and humans may ally temporarily to deal with an even higher predator in the food chain, but it would kinda defeat the point of the plot. So the question is how to make some enemies attack others selectively, without humans being caught in the crossfire.
And at some point the humans will have to regain some territory… they will run out of resources if they stay cooped up in that fort.