During PAX 2009, we stopped by Valve's booth to chat with Chet Faliszek, one of the leading minds behind Left 4 Dead 2. Read on for insight into the differences between Left 4 Dead and its upcoming sequel, the possibility of user-created levels on Xbox 360 and just what's possible with the L4D2 editing tools: So, you guys have talked about fleshing out the story in Left 4 Dead 2 a bit more, and having a more involved plot. How do you do that with a game like this? I think that's one of those "I'm just going to ask you to wait and see." Some of it is simply ... Left 4 Dead 1's world was at the same stage every place you went. The infection had been there for a little bit. This time we're seeing what it's like to be in a city before the infection hits. And you see different people's reaction to that, as you cross around the country, and there's some other bits we tie in with the original Left 4 Dead in Left 4 Dead 2 as well.