Updates to Left 4 Dead have been released. The updates will be applied automatically when your Steam client is restarted. The major changes include:

Left 4 Dead
Fixed campaign image not updating correctly when creating a lobby
Increased the reliabilty of the Steam Group server display
Made mm_dedicated_search_maxping available to allow users to set the maximum acceptable ping for a dedicated server. The default has also been lowered 150ms, down from 300ms
Fixed an issue where rescue closet doors could be opened in Crash Course in Versus mode
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