Valve is planning another downloadable content pack for Left 4 Dead 2. Today they shared some details on what this unnamed DLC will entail.

"The very first step in creating a new DLC is deciding on the larger goals and constraints for the DLC," said Valve on the L4D Blog. "The Sacrifice and the Passing were story heavy, so we want to see what the other end of the spectrum looks like. For this DLC we start with wanting to experiment by releasing a map pack that wasn’t about story. It would just be new campaigns for Left 4 Dead 2. "

The DLC pack will add the three remaining Left 4 Dead campaigns to L4D2. It will also include "Cold Stream," a new community campaign from "2 Evil Eyes" creator Matthew Lourdelet. Valve says this is just "the start of the DLC," though.

The new content will arrive sometime after Portal 2 - in other words, late April at the earliest. Testing for "Cold Stream" will begin within the next few weeks.