Actualy, would the Martians need anything more than their heat ray? If they didn't use it, I don't know what I'll do to Spielberg.
It's an unbelievably terrifying weapon and nothing you can do will save you from being struck down by it. ANYWHERE you go, it'll find you. A key element of the story I think.
Don't want bombed out buildings, want something beyond my wildest imaginings, something unnatural, inescapable.