2. Emotion
When I was playing 'The Walking Dead' I felt a true emotional connection to a story in a way that could not ever EVER have been achieved in any medium other than video-games. I'll be the first to admit that it isn't exactly the first time I've felt that kind of connection (I think 'Heavy Rain' was the first game to ever make me actually feel remorse for the things I was doing in a digital world and represents, in my opinion, a pinnacle for video-games as a form of art instead of entertainment) but one thing I 'll say is that The Walking Dead is one of the biggest steps forward in video-games as a story-telling medium ever.
3. Character Relationships/Interactions
The game's main protagonist Lee Everett, is a bit of a mystery: he has a criminal past that we don't quite understand, and even though we don't know what he's done, we're forced to make decisions about how clean we want to come to the other survivors. Some of them take him at his word, others are suspicious. His relationships with his family and his ex-wife are complicated, and we learn about them through casually tossed off bits of conversation and, at some points, grisly discoveries in the game. The game is primarily concerned with telling Lee's story, but the other characters I met offered just enough in their limited screen time to make me interested in them, as the group grows and fights through adversity. And the young girl Clementine (who I'll get to in a minute) is another well-done, real-feeling character. Best of all, the game features Glenn, who is by far the least-toolish character on the TV show.