Well, not quite sure if this actually counts as a horror genre game, bur it has a witch in it, so we'll let it slide.
The name of the game is Gun Witch, and to be honest I have no idea what the story is about. All I know is there is a woman running around a monster infested city in a slinky dress and she can cast spells...And she's kicking demon ass with this HUGE ass gun! I mean, its almost as big as her!
Anyway, here is a link to a bunch of pics and videos of the game, including trailers and actual gameplay. In fact, one of the videos is about 6 minutes long of nothing but gameplay. Check out the part where she's in the city fighting that gigantic boss, the one nearly as big as the buildings around her!
http://www.xboxyde.com/game_944_en.html
Currently, its planned as Japan only, but the development company is shopping for a publisher for here in the states and the UK, so maybe it will wind up like Phantom Dust for the Xbox. Here's hoping because this game looks pretty cool. I mean, women, violence, magic and big ass guns...What's not to love? :D