- Viaduct has been haunted and is now... Eyeaduct!
- One full multi-piece costume set has been added for each class
- Random gifts containing costume pieces drop in Eyeaduct on registered servers
- 2 new Halloween 2011 achievements
- Any unusual hats uncrated during the event will be Halloween-themed
- New Halloween-themed items are available in the Mann Co. store, but only for a limited time!
- Updated effects for The Cow Mangler 5000
- Updated in-game abuse reporting tool to include option for reporting abusive game servers
mapcycle_halloweencontaining all Halloween event maps
- Fixed team colors and styles not updating properly in store previews
- Fixed bug in reputation trend status display for registered servers
- Fixed a problem that could cause repeated stutters after joining a server
- Fixed the Spine-Chilling Skull not appearing when equipped by soldiers
- New Halloween-themed community-created items submitted to the Workshop are now available in the Mann Co. store!
- All Ghastly Gibuses have been upgraded to Ghastlier Gibuses. Ghastlier Gibuses have been upgraded to the new Ghastlierest Gibuses.
- The Halloween 2010 Noisemakers have been made re-availaible in the MannCo Store
- Hitting the Horseless Headless Horsemann now plays a hitsound, as if you had hit a player.
- All hats that had Halloween restrictions can now be worn on an actual full moon.
A good description by Problem on SPUF on how the new stuff works.