Free on Steam this weekend: Dreamkiller
I don't use Steam, nor have I ever played this game, so I can't really vouch for this deal. I'm sharing because free is free :)
Update: furythree has posted in the comments that this 'full game' is only valid until Monday, after which you need to buy it. This makes it a glorified trial. Unless you want to waste your bandwidth downloading it and then finishing it within a day or 2, don't bother with it!
Official website: http://www.dreamkillergame.com/
Wikipedia blurb:
Dreamkiller is a fantasy first-person shooter where the player takes on the role of Alice Drake, a psychologist with the ability to enter the minds of her patients to fight the monsters appearing in their dreams. The game is developed by Mindware Studios and published by Aspyr for Xbox 360 and Microsoft Windows.
Developer(s): Mindware Studios
Publisher(s): Aspyr
Platform(s): Xbox 360, Microsoft Windows
Release date(s): October 2009
Genre(s): Fantasy First-person shooter
Mode(s): Single-player, Multi-player
Rating(s): ESRB: Mature
Not sure why some of the text ended up huge, so if any mods are around, can you fix it for me? :)