Personally I love a good war game, and am also a big fan of the horror genre (not at night-time though). Hence, I really enjoyed Anderson and the Legacy of Cthulhu as it manages to blend the two to good effect. Part of the appeal of the game is the interesting way it blends story narration with creepy gameplay to create a unique interactive experience.
You simply click on a chapter of the book to enter the narration before being whisked into battle in the way you would in a normal action game. Graphically, the game makes good use of lighting effects to keep things pretty eerie, although the backgrounds and characters are a little simplistic. That said, Anderson and the Legacy of Cthulhu boasts a cracking soundtrack that's enough to put the willies up even the most hardened horror fan.