Valve's Chet Faliszek has told Eurogamer that upcoming downloadable Left 4 Dead 1 expansion Crash Course costs money on Xbox Live because Microsoft insisted upon it. The Washington-based developer traditionally refuses to charge for DLC - as Robin Walker put it when we asked in May 2007, "You buy the product, you get the content" - and this explains why it's free on PC.

"We own our platform, Steam. Microsoft owns their platform. They wanted to make sure there's an economy of value there," Faliszek told Eurogamer today when asked about the 560 Microsoft Points (£4.76 / €6.72) price tag for Crash Course.

When pressed about whether Microsoft effectively enforced the pricing, Faliszek added: "Well, they helped us get the first one out for free. We had the one DLC out for free. And I think... they have to look and say, wow, we're kind of being unfair to everybody else if these guys can do that.

"It's not like we're [Valve is] looking at this as, 'Oh my god, we need some money, we're going to charge,' obviously, or we'd do it on the PC. So it's just kind of the way the system works right now."

Crash Course is an upcoming campaign for Left 4 Dead 1 that's been designed not exclusively but predominantly for Versus mode, which should allow fans of the competitive survivors-versus-infected mode to play through a game in 30 minutes rather than the two hours it sometimes takes with No Mercy, Dead Air, Death Toll and Blood Harvest, the original campaigns.

Read the entire article in EuroGamer.