An experience that will remain with a player, long after the credits roll is, in my opinion, the effectiveness of the story. Truly great games stick with you because of memorable story elements that made you laugh, smile or cry.
Mad Men currently is a winner of 15 Emmy Awards, with three for writing. Breaking Bad is a winner of 10 Emmy Awards with six for acting. Both are praiseworthy, but The Walking Dead is equal parts high-caliber acting and high-caliber writing.