The check is done by taking the thief's open lock skill and adding a random 2-9, then comparing against the lock's difficulty.
So, as you can see, even if you somehow had an open lock score of 0, you'd have a 50% chance of opening any lock. And it's impossible to be a thief and have less than a base 18% lockpick skill. A 5th level thief, which requires all of 10k xp, most of which is given to you just during the process of becoming a thief, and that distributed his skills evenly, should have at least 45% open locks skill.
Again - pretty much every pickable lock in game has a difficulty of -5-. That's -five-.
Would you consider this to be broken and in need of fixing? Or do you think I should assume this was intended and not touch it? That's the choice in this question. Me, I'm thinking they were set that low during debugging/testing of the game and never set back to where they were supposed to be.
The fix I'm contemplating is to multiply the difficulty of the locks by a factor of 10. So that difficulty 5 lock would instead have a difficulty of 50 - which should still be easy for most thieves and a cakewalk for Annah (who comes with 68% lockpick to start with, I believe), but at least it's not absurdly easy.
As it stands, there is no reason to ever pump a point into open locks skill. Just by being a thief you can't fail opening any lock in the game that I'm aware of that can be picked at all.
The traps in game have more reasonable values. Still pretty easy, but not absurdly easy. Not planning on changing those at this time.
Qwinn
Edited by Qwinn, 05 September 2008 - 01:59 PM.