Well what can I say.. I suppose its just Jim..
But it's a bit disappointing.
Let me start by saying that I don't think the walking dead is a bad game. It is, arguably the best adventure game I can think of, and the writing, and characters are rather excellent. The story is also well told (if a bit stretched through some of the episodes), and the conclusion is great even if I felt it was a bit theatrical and was expecting it for a while. Anyhow it is what it is, a great, thoughtfully written "chose your own adventure book" made out of cutscenes. And that is AS FAR AS THE GAME CAN BE CONSIDERED GOOD.
The game in its GAME aspect, is extremely weak. It does no strides to bring mechanics up to par with the narrative like Spec Ops does, it exposes bluntly rather than imply subtly as Journey does, and in the end, it feels just like an extremely static movie where you can switch play a different chapter in specific points of the game.
In fact it even holds back the interesting growing trend of active unconscious decision-making in favor of a spread sheet dialogue tree structure.
It presents dramatically the weaknesses of the genre too, in many situations forcing you to solve a problem in a manner so structured that it becomes obtuse, with inadequate control mechanics akin to the messy Heavy Rain, and often not even allowing the option to react as one would (like Mass effect's "choice").
I know it's a very Nintendo fanboy card to play, but games are about Gameplay, and gameplay should enhance the experience of the story. In the Walking dead, there is no gameplay to speak of, and when it's here, it rarely ever enhances the experience.
For a game of the year award, I think its a necessity to ask the questions: Could this Game be done in another medium? and, is this better for being a game? And in this particular case I think the answer is that we could very well see this game as an "interactive tv show", and even a less frustrating literal chose your own adventure book.
Considering that a few games this year managed to drive the medium forward with experiences that cannot exist outside the medium itself, and also manage to have a profound emotional impact (really, this was good but it often bordered on cheesyness) it seems like the wrong pick.. but well, maybe that's just me.