As you sprint through the streets towards whatever emanated the sound, a thick cloud of ashen dust and mist billows in front of you as you enter one particular street which is covered in rubble, the sinister mass of gas stretching high over your head. It must have come from the fallen skyscrapers... There is an eerie silence as the grey cloud slowly rolls toward you. Then, from behind the husk of an obliterated building engulfed in the cloud, the silhouette of a gigantic mechanical appendage swings into view, dimmed behind the smoke. It stomps down into the cement below it with a deafening crumble, and past it swings another gigantic appendage. They are a pair of legs. You cannot see what walks upon them, for the cloud in front of you stretches too high over your head to see what it could be.