!!!!!EPILEPSY WARNING!!!!! You want to know what this is. You want to know what it is. You want to know what it is that is destroying the cities. You want to know how it does it. You want to know the method of which it uses to demolish these civilizations. This cannot be known. Whatever "this" is, it cannot be known. Perhaps it is a reaper, returning the towering steel to the earth. Perhaps it is a flood, washing everything away and leaving nothing behind. But does it matter what it is? Whatever it is, it is destroying the city. You don't know how. I don't know how. Did the citizens learn how? Perhaps they did, but I think not. Either way, it doesn't matter now. Whatever knowledge they had in the end, it is lost now. Could this knowledge be recovered? Could the CITIES be recovered? Perhaps they could, but I think not. After all, you know nothing of... Whatever this is. Is it an it? Is it a force of nature, or are they a person? Or... Is this something other? What is it? How can this terrible calamity escape us, again and again? I know nothing more of this than you do. You will never know more of this than I do now. It doesn't matter, anyway. All that matters is the cities, which are no longer there. (I considered spending longer on this, but I mean, I doubt a formless cosmic horror is gonna win anyway.)