October 4, 2011 Patch

{{Patch layout
 * source =
 * source-title =


 * before = September 12, 2011 Patch
 * after = N/A


 * notes =

Undocumented changes
}}
 * Added a new Co-op lobby.
 * Added a new Co-op track, Art Therapy.
 * Added Challenge levels for Singleplayer and Co-op.