Trying to set itself aside from being just another first-person shooter, one of the unique aspects of 2K's The Darkness are what is called The Creeping Dark. Here's a good description of this little bastard:
Creeping Dark, the snake-like appendage that slides along the ground, up the walls and through windows in The Darkness, can be used to attack Uncle Paulie’s hitmen and devour their hearts, open locked doors, and much more.
Funny enough, just as 2K sent this to our inbox this morning, I actually have an appointment with them today to get some quality hands-on time with this upcoming title. Stay tuned to find out how that goes.