Blackwell Deception Free - Until 11:59pm 11/01/2013
From Blues News:
Wadjeteye Games is offering a treat this Halloween, as they are offering their point-and-click adventure Blackwell Deception as a free download through tomorrow. Between now and 11:59 pm EDT tomorrow all you need to do is add the game to your shopping cart on their website and enter the code "Boo" into the discount area and the game's price will be zeroed out. Here's a reminder of what this series involves: "Wadjet Eye's Blackwell adventure games star Rosa Blackwell, a spirit medium committed to helping troubled souls cross over, and her spectral sidekick Joey Mallone. The duo has appeared in four indie adventure games since 2006: The Blackwell Legacy, Blackwell Unbound, Blackwell Convergence, and Blackwell Deception."
http://www.bluesnews.com/s/146363/blackwell-deception-free
The link to Wadjeteya Games is here:
http://www.wadjeteyegames.com/blackwell-deception.html
I've never played any of these and have no idea of how good they are but for free, it has to be worth a try 
Edit - Added the expiration of the offer to the title.