It's the Creative Director of Supergiant Games. 
These are the guys that gave Giant Bomb the exclusive on what their game is going to be -   
 
  Found on the Developer website - 

Bastion  will also be featured in a new video series chronicling the making of the game, exclusively at GiantBomb.com, the world’s largest editable video game database. In the ongoing series titled “ Building the Bastion “, viewers will receive unprecedented insight into the trials and tribulations of independent game development through the story of Supergiant Games.  
“People all over the world invest countless hours into playing video games, but so few of us ever get to truly find out how they’re made,” said Giant Bomb Editor-in-Chief Jeff Gerstmann. “With  Building the Bastion , we’re going let our community ride shotgun with a mix of behind-the-scenes footage and regular live broadcasts that let you interact directly with the developers as they take  Bastion  from early prototypes to a full and final product.” 

Dude! Awesome news, thanks for sharing this.

Interesting. How long has this been in development? Wasn't he working on the new Spec Ops?

Yea what happened to him and The Line? 
 
Come to think about it, what happened to The Line?

I rather like the picture for the game and since he is attached im automatically more interested. I cant wait to hear what type of game it is and, with a lot of luck, see it in action.

@Fjordson:

When I saw this on his twitter I was like 
 

AH DAMN IT'S ON NOW

RA3 > Spec Ops > Bastion > ???

Bumping for new video feature.

Why is greg kasavin writing all the dialogue a good thing? I know he wrote reviews a while ago, but what other fiction has he written?

" Why is greg kasavin writing all the dialogue a good thing? I know he wrote reviews a while ago, but what other fiction has he written? "

Supergiant Games? 
They're totally trying to one-up Big Huge Games, aren't they? Hope to see a MegaMassive Games and TotallyEnormous Games studio pop up soon, too.

He quit his 2K job and found a new game developer job? :(
 
Hello GregK,
 
Please choose Giant Bomb for your next job. You know you want to.

" Why is greg kasavin writing all the dialogue a good thing? I know he wrote reviews a while ago, but what other fiction has he written? "

Bastion is going to be pretty savage.

I'm so fucking stoked for this game. Doubly now that I know Greg K is involved and that they're running a feature on GB for it. Awesome!

Everything about the OP made me go ":D!"

That's really cool. I'm excited for the video content and the game. 

Ahh, cool news. Greg was my favorite GameSpot Editor. Sad when he left to develop games... He makes very good and informative reviews.
 
I guess that doesn't matter now since that's a long time ago. I'll need to take a look at this game when it comes out.

reminds me of the art style from Legend of Mana and other Brownie Brown games.

I congratulated him on Twitter. This is amazing, and I'm so glad to see that Giant Bomb is getting some awesome exclusive content from Bastion, which looks genuinely cool.

I twigged this after the initial announcement of Bastion and seeing that 'GregK' had edited the company's wiki and that on his blog he was announcing moving on to a new indie project.  Exciting stuff.
 
This is a really interesting approach to market a game.  I'm trying to work if the close ties and exclusivity to Giantbomb specifically are losing Supergiant games anything by not reaching out to the wider gaming press as much.  However, if this a decently sized video series then I can see a lot of Giantbomb viewers getting invested in this game just by watching the development process and then wanting to buy the game no matter what just to see how it turned out compared to the work we saw go into it.  Especially if GB users spread the game word of mouth this could be a really smart move in guaranteeing a core audience.
 
Also, I can't think of a more interesting form of new video content for GB.  Going to be one of the things I most look forward to from now on.

Is he still working on Spec Ops: The Line?

Oh man! New game content that'll give us an inside look into Bastion!
I am already in love with the game, what with Giantbomb getting the exclusives AND the released content. 

Now that you mention it, all of the voice work in that original trailer sounds like the guy is one sentence away from saying "savagery."  This is definitely good news. 

Good to hear.  I always wanted another Indievelopment style video series.

Wow, creative director? Good to see that Kasavin is doing so well for himself.

That's pretty awesome.  I have always liked Greg over the years and wish him all the best in his newest venture in life.

Ah, that explains the coverage for this game.

"Isn't he lurking around on this site with a mere 6 posts or so? I'm not sure if that's him or some random imposter. "

that's too bad about his work at SpecOps. I guess if a job comes around with a better title and a pay upgrade you take it. 

" @CitizenKane: Woah! Double post there! =O  And gratz to Greg. Isn't he lurking around on this site with a mere 6 posts or so? I'm not sure if that's him or some random imposter. "

That's pretty sweet. Hope it turns out well.

Well I'll be a fart in the wind, good for him. If Greg were a video game, he would be a classic.

" Well I'll be a fart in the wind, good for him. If Greg were a video game, he would be a classic. "

" that's too bad about his work at SpecOps. I guess if a job comes around with a better title and a pay upgrade you take it.  "

A new job? I don't recall him retiring from the Master of Masterness occupation.

Greg Kasavin > Ben "Yahtzee" Croshaw 
 
There, I said it fanboys! 
 
Go ahead and flame me!

Go Greg! This game looks pretty crazy. I think I'll buy it just to support my homie's creative genius. Still keepin' it real for the Gregmaster K!

Greg Kasavin was always among my favorite GameSpot editors/reviewers so I am obligated to be at the very least, be interested in this new game.  Anyone who takes game narratives seriously deserve respect.

Okay, but I'm still looking forward to Spec Ops.

So this is why his blog about game stories came about. Neat.
 
But it's not quite the type of game I think of when I think Greg Kasavin.

Well, this explains the exclusive Giant Bomb coverage. Now I have to start caring about Bastion.

Um, wait...  So is he not working on The Line anymore, or is he handling both projects?

Finally I can say that Spec Ops: The Line looks pretty mediocre and cliche without feeling like a jack-ass.