Thieves Can Climb Walls

[DerVVulfman]

The rating difference of one foothold to another and the player's skill level. The increase of the player's level, learned skills, and equipment can increase their chance of holding on, but a foothold may be set to a more difficult rating.

Or he just lets go of [SHIFT] by accident...

I figure an intrepid scripter can find the itty bitty widdle switch that makes them fall and set a timer or something.