[Another neat GSW-xpost from our E3 coverage -- with Valve's announcement of Left 4 Dead 2 coming just a year after its predecessor, Chris Remo spoke with project lead Tom Leonard about why the sequel is coming so soon -- and what it means for the original game.]

Valve's big E3 announcement -- that last year's hit Left 4 Dead would be followed up with a PC and Xbox 360 sequel this year -- was a surprise coming from a studio that has never delivered a full sequel in such a short timeframe.

It was made even more notable by Valve's oft-stated strategy of supporting its multiplayer games with new content and updates for many months or even years after their release, as exemplified by the ever-evolving Team Fortress 2.

At E3, as part of a longer forthcoming interview, we caught up with Tom Leonard, Valve developer and project lead on Left 4 Dead 2, to discuss the reason for the quick turnaround -- and the fate of the original Left 4 Dead.

"There's definitely not a change in policy," said Leonard in response to Gamasutra's inquiries as to whether this move represents a new direction for Valve's multiplayer efforts.

He pointed out that Valve has always experimented with different types of development and distribution. "With the various things we've done -- Half-Life 2, the big splash game that takes forever; or the episodic content; or the [Team Fortress 2] updates -- as a company we try to explore different ways of delivering value to the customer," he explained.

"For the team I'm working on, it was perceived that the best way to provide value was to provide this big experience."

Development on Left 4 Dead 2 began almost immediately after the first game shipped, following a short break, but the idea of a standalone sequel was borne out of necessity and practicality.

"The team got back together in early November, and we were all really excited to continue to expand the Left 4 Dead experience," Leonard recalled. "We hit the white board and came up with ideas about how we could expand the experience -- new characters, new locations, new positioning on the timeline of the infection, new game mechanics."

"As we started talking that through, it became clear that we weren't really talking about incremental updates; we were talking about a whole experience. And it would be hard to deliver that totality of experience in incremental bits."

"So I proposed to people, 'Why don't we try to make a sequel and do it in a year?' Everyone thought I was crazy, but as I talked them through the strategy of how to do it, the team collectively said, 'Yeah, that's interesting.'"

Leonard and the rest of the team discussed the idea with marketing VP Doug Lombardi and studio founder Gabe Newell, and were given the green light to proceed: "They said, 'Sounds great, if that's what you want to do.' Basically, the team was motivated to create an entire package."

But what about Left 4 Dead, which some players expect to fall by the wayside in the wake of its sequel?

Leonard declined to commit to there being more Valve-created content for the game, instead pointing out some upcoming functionality tweaks and the potential in user-created levels for the PC version. "We are doing updates across the summer, adding new matchmaking features, and new features to facilitate user maps after the SDK is out," he said. "Certainly, user maps will be part of the ongoing Left 4 Dead 1 experience."

"Additionally, those maps can be transported into Left 4 Dead 2. With regard to more content, it's hard to say, because the timeline for Left 4 Dead 2 is so sensitive, and the team has a head of steam right now for the game."