A select piece from the interview, make certain to check it out in full:

GFW: Granted, there's a lot more to Half-Life's story than who and what the G-Man is, but it seems that the longer those questions go unanswered, the less likely you'll be able to answer them to everyone's satisfaction.

GN: We have some good answers. I totally recognize, though, that you can't become excessively cautious and fearful that the reason people are interested in what's happening is the mystery. Because that just means you're avoiding the ongoing problem of telling new stories and creating new characters. I think people are worried, like, what happens if we kill off characters? I was just responding to an e-mail from a fan who had this idea that somehow we could bring Eli Vance back, and I was like, "No, he's dead!" He really is dead. People die in this universe; it's not a kids' TV show where the cast of characters is static, and what can happen to them is constrained by the fact that customers are able to view the TV shows out of order, right? Which is a horrible constraint to put on TV writers. That's something we've never had to deal with.

GFW: How far in advance did you decide Eli's fate?

GN: A pretty long time. There's a difference between plot points and character arcs and other decisions that we make about set-pieces and weapons, which tend to be plastic, as opposed to story stuff, which we need to work out in order to build toward conclusions and a sense of closure. It's a lot easier to produce smaller stories like Portal.

GFW: Are you interested in producing more stories of Portal's sort?

GN: The interesting thing about Portal is that we know who the protagonist, Chell, is, and we'd already planned that character's part in something that occurs later. With Portal, we sort of opportunistically said, "Oh, she fits in here. This makes sense.