AmEx has always had a ton of silly deals/coupons/rebates/handjobs/whatever going for their customers. Maybe that's why old people always seem to carry the card - if clipping coupons is an efficient expenditure of your time then I guess jumping through hoops for AmEx would be equally stimulating. It almost makes you forget the fact that you're paying $$$/year for a service that you could get for free (or near enough) elsewhere.
Otherwise, this is a pretty cool promotion. It won't influence my decision to buy the game or get an AmEx card, but it sounds like a pretty solid way for AmEx to reach out to an audience that can still chew their own food.