What was the machine used for in Amnesia: A Machine for Pigs?
From a wiki entry -
"After he returned from his Mexican expedition, Mandus was consumed with obsession over a vision of the future from "the egg," hinted to be an Orb, in which both of his children killed at the Battle of the Somme. Driven mad by the vision, Mandus decided that he could not allow it to come to pass, and he built the Machine to create a godlike being via mass ritual human sacrifice to save humanity from its own carnage. He then killed Edwin and Enoch himself to spare their fate at the Somme."