Amid a growing online petition, 16,571 Members strong at the time of writing, that pledges to boycott the game, Valve has defended its decision to release Left 4 Dead 2.

Left 4 Dead 2, scheduled for release this November for Xbox 360 and PC, adds five new campaigns, four new characters, a new setting, melee weapons, new Infected, location-based damage, a new version of the AI director and a new unannounced game mode.

The 'L4D2 Boycott' group has outlined a raft of complaints on the Steam forums. It believes the announced content of Left 4 Dead 2 does not warrant a stand-alone, full-priced sequel and should instead become updates (free or otherwise) for Left 4 Dead.

Speaking to at E3 last week, writer Chet Faliszek said that Left 4 Dead 2, which was originally called "this big thing" by the development team, is a large enough game to justify it not being DLC, pointing to all the new announced content.

He said: "It was just like, OK, this is big enough that this isn't DLC, we're not going to be able to leak it out. It's a cohesive, single thing. It's Left 4 Dead 2."

Faliszek also promised Left 4 Dead fans that updates are still due for the original. "In fact Left 4 Dead one, we still aren't done with it," he said. "We still have updates coming. Our focus is always on what we're putting in the box, put as much as we can in the box. Let's not worry about: let's save that and not put that in the game. No, let's put that in. And with the five campaigns, all of them out of the box, playable Versus, co-op, Survival and the new mode, there's just a ton of content in there."

When asked if Left 4 Dead had now become an annually updated franchise, and whether 2010 would see the release of Left 4 Dead 3, Faliszek replied: "We do it once in a year and everyone's like, oh my God! Let's do this one. Let's worry about this and then we'll see."

What do you think? Is Chet Faliszek right? Let us know in the comments section below.