So are these abilities done? Is it a fixed percentage, a skill point pool, or an attribute check?
Thief abilities are handled similarly to Basic D&D’s saving throws. For each type of thief ability, you have a target value for a roll of 1d20.
For example, you might have “Find/Remove Trap 14+”. To search for traps, you’d roll 1d20 and on a result of 14 or higher you found the trap (if any). A particularly cunning trap might impose a penalty on the die roll.
Another example might be “Climb Walls 6+”. To climb walls, you’d roll 1d20 and on a result of 6 or higher you scaled the wall (or portion thereof). A particularly smooth, slick, or inclined wall might impose a penalty on the die roll.
If you calculate the exact percentages of success on thief throws, they map closely (but not perfectly) to the percentages used in Moldvay/Cook B/X.
So does every class have a Climb throw? Or only some?
I’m a new guy who just discovered ACKS last night and read your entire blog today. I’m hoping there’s a generic rule for adventuring skills that all classes can do.
Not all classes have climbing throws. Other classes can’t climb sheer walls without the help of ropes and similar (for which there is no check).
…or the Climbing or Mountaineering proficiencies.
(On the class lists for: Assassin and Explorer - although Mountaineering seems mostly weaker than Climbing?)