Portal is one of the most charming success stories of 2007. The game's creativity and heart is matched by its high quality -- and that's all backed by a romantic story of a bunch of students improbably scooped up and allowed to let their vision blossom at a top-tier studio.

At GDC, Gamasutra had a chance to speak to Kim Swift and Erik Wolpaw, the game's lead designer and lead writer, shortly after the game won three major Game Developers Choice Awards - including Best Game Design, Innovation, and Game Of The Year.

Over the course of the conversation, the topics of how its unique narrative-linked design came about, the strengths of working at Valve, and even the possibility of Portal DS were discussed.

How do you feel after the awards? Did you expect that you were going to get that many?

Kim Swift: No, we definitely did not. We're pretty damn happy, I'd say.

Erik Wolpaw: Yeah, it's been kind of shocking. It's a shock. I don't think anybody really expects that they're going to win something like that.

KS: And the fact that it's game developers who are doing the voting and making the choice for the awards makes it all the more significant.

I thought it was interesting that a lot of the games in the innovation and downloadable categories were previous IGF or student showcase titles. Did you notice that?

KS: Yeah, I did. That's pretty cool. Being in a similar position, having Narbacular Drop become Portal... it's a wonderful thing to see, with people trying new things and being successful, and being able to put their ideas out there and accepted.

About your process... I was really impressed with the way that the narrative and the game design was well implemented. I'm wondering how you came to that.

KS: Well, we had a half an hour speech about that. (laughs)

EW: It was one of our goals. It was a goal that we had, to tightly integrate the gameplay and the story together, but it would be actually easier to do that in some ways because of all the constraints we were under. We were a small team, and we have all the resources at Valve at our disposal.

That helped, but a lot of people were busy releasing three products at once. Some of that was planned, and some of that was a way to creatively sidestep the restraints we had.

KS: A lot of it came out of the fact that we playtested our game every single week. We were watching people play the game and seeing how they reacted to certain situations, and tried to play up how they were feeling at the time with the dialogue and different turning points in the story. We definitely had our players and our customers in mind when we were making the game.

What really impressed me specifically about the story was the way that the two were really one and the same, kind of. There was no exposition, really. The way that you found out about the world was by things that were there. I was wondering if that was design-driven or writer-driven, or was it a combination of the two?

KS: I'd say a little from column A and a little from column B.

EW: The combination of the two. It goes back to the playtesting again. The playtesting helps test the gameplay, but at the end of the playtest, we'd also ask people to tell us the story back. "Tell us everything that you remember about the story."

If enough people weren't picking up on things, generally speaking, it was an indication to us that they just didn't care about it, which meant we should probably either cut it or in some cases where we didn't really want to let it go...

KS: Make it better.

EW: Well, it served us better usually to cut it. We generally found that if we added more of it, people just tuned out more. Usually, if they weren't interested enough to pay attention to it, it was better just to cut it. Although sometimes we would try and move it into the environment itself. In other words, instead of having somebody talk about it, or GLaDOS say something, we could just maybe offload it into the environment somewhere.

When I first got behind the world... up until the point, I was just playing the game, and then when that was there, it was like, "Oh, there's definitely a lot more here." Obviously in the game design, but also in terms of the emotions felt, it felt like things were revealed very carefully in a sophisticated way. I've been telling people that I feel like Portal is one of the more sophisticated narrative-driven games, even though it's hard to call it that, really, because it's just actually well-realized.

KS: Thank you! (laughs)

EW: That's a nice thing to say.

KS: It definitely has a lot to do with process and the fact that we sat down to watch people play our game. It's really incredible, how much information you can get just from watching someone play your game that hasn't played it before.

Seeing what they think about the game and watching the expressions on their face, you can tell if they're happy with what they're feeling, or if they're bored or if they're sad. We were always very deliberately watching our players to see how we could make the experience better for them.