Fans drawn in by Thrones’ sprawling narrative may find themselves disappointed by a binary ending. — Now that Game of Thrones has returned to the screen, the search is on for breadcrumbs that point to how the show will end. But instead of rereading the books or scouring public interviews, hardcore fans could learn something from a turn-of-the-decade video game. Mass Effect, the sprawling, critically-acclaimed action-RPG…