Through an interview with Chet Faliszek, writer of Left 4 Dead, our colleagues from Kotaku have learned more about the additional content created by Valve. In theory, this additional content should be announced before Christmas, but with the studio in Seattle, the delay is nothing alarming.

Downloadable content should be available simultaneously on PC and Xbox 360, which will please players Valve console since we had used to offset outflows with Team Fortress 2. Among the news, we note the presence of new scenarios (without knowing how much), the opportunity to play the campaigns' death warrant 'and' Air Holes' versus mode.

PC players should also be able to count on the famous SDK: a tool that Valve has promised long ago and will create their own maps, scenarios and mods. Expected to be free on PC (the way of what Valve has already been a while), the content may be paying for Xbox 360 because Microsoft push publishers to charge such initiatives. Now to have confirmation ... and the date!