Many are the horror games that involve you going down. Down is where much of the Badness in the world is traditionally located, after all, whether you're talking about geology or psychology or theology. White Knuckle reverses the flow. You are already Down; by extrapolation, you must now go Up.
Possibly, you are Down because you are a manifestation of the aforementioned Badness. Possibly, the monstrous things trying to thwart your ascent are merely trying to stop you contaminating the surface world. Possibly, they are the Real Heroes. It doesn't really matter, because you don't have a choice. There is a wall of unspeakable flesh coming up the tunnel behind you. To avoid becoming part of it, you must climb.