The song tells the tale of a man who travels in time to save mankind, but in the process is turned to steel, to an iron man (although iron is not the same as steel and the song also states that his boots are made of lead). This form leaves him in a vegetative state where it is unclear, if he is even still alive. It is presumed that he’s dead, so everyone ungratefully just leaves him there, however Iron man is still alive. Lying there in his metal shell he plans vengance on the people who don’t acknowledge his heroism. Finally the time comes, Iron man lives again, and alone he goes on a dreadful rampage killing everyone.
From the Wikipedia entry on Iron Man (song).
God bless Wikipedia. And God bless Guitar Hero, for making me wonder what the hell that song is about, anyway.
I was just playing and wondering about that very song yesterday.