Um...so we're looking at The Devil's Double, mixed with Majin and the Forsaken Kingdom, and Slaughterhouse 5 by Kurt Vonnegut...
That is one royal mess of a game/film/book you have on your hands :| Um...a world war 2 survivor who might, or might not have been abducted by aliens is forced into being the body double of Saddam Hussein's son, but in a quest to win back Iraq from "the darkness" he joins forces with the mystical "guardian", a forest creature of legend....i smell oscar success!!!
Get me Jackson on the fone, right now!!