Valve has released the long awaited software development tools for Left 4 Dead. The tools are available via the tools tab in Steam.
The SDK tools allow modders to create their own levels or full campaigns. The SDK includes the Hammer level editor and a particle editor as well as example maps and particle systems.
Valve will be updating their matchmaking system to work with the new user created content. They have also created a Wiki for anybody interested in using the tools. The SDK is in open beta now and is only available for the PC version of Left 4 Dead. We can’t wait to see what the modders are going to come with.