I posted most of this stuff at one point or another in the old forums, but since that forum is gone and not archived despite official statements to the contrary, I figured it'd be nice to have it all in one place here. All the info here is for the PC version; I can't promise it's the same on consoles.
TABLE OF CONTENTS
I: Stealth
II: Stealing
III: Lockpicking
IV: Traps
V: Coercion
I: STEALTH
This information comes from skill_stealth.nss, sys_stealth_h.nss, and rules_core.nss.
Your success at entering stealth seems to be deterministic (i.e. not random) and obeys a simple algorithm. Consult the following table to see whether fortune smiles upon you today:
http://i46.tinypic.com/10r7rwi.jpg
For clarity's sake, I'll also write out the algorithm below. Go through the steps below in order to figure out whether you can stealth or not:
Step 1: Am I in combat? If not, SUCCESS.
Step 2: Are there no enemies within 20m? If not, SUCCESS.
Step 3: Do I have Combat Stealth? If not, FAIL.
Step 4: Is my stealth rank greater than the rank of the highest ranked creature within perception range? If not, FAIL.
Step 5: SUCCESS
"Stealth rank" is the number of points you have in the stealth tree. Combat Stealth is rank 3 and Master Stealth is rank 4. For stealth purposes, "Creature rank" is 1 for whites, 2 for yellows, 3 for bosses, and 4 for 1337 bosses.
Notice that cunning appears to play no part in determining whether you can enter stealth or not.
What happens if you get damaged while stealthed (e.g. by a trap)? If you only have stealth rank 1 or 2, you automatically break stealth. If you have stealth rank 3, you have a 0.01 * [player level] chance of staying stealthed (e.g. a level 18 rogue has an 18% chance). If you have stealth rank 4, you have a 0.02 * [player level] chance of staying stealthed (e.g. a level 18 rogue has a 36% chance).
I haven't been able to figure out what is your chance of staying cloaked while laying traps. This seems to be nondeterministic; sometimes it fails, but when I reload and try again it works. It's possible that this chance is affected by cunning, but I can't find the code anywhere.
II: STEALING
This information comes from skill_stealing.nss.
When attempting to steal, the game calculates a thief score (T) and a victim score (V) and compares the two. If T > V, the attempt is a success; otherwise it's a failure. The thief score depends on the player's cunning, ranks in Stealing, and his ranks in Stealth (if he is stealthed). The victim score depends on the victim's mental resistance, rank, whether or not either actor is in combat, and the difference between the thief's level and the victim's level.
The formula for thief score is:
T = (cunning - 10) + 5 * [ranks in stealing] + 5 * [points in stealth if stealthed]
As you can see, each point in Stealing or Stealth is worth 5 points in cunning. One point in Stealth is worth a rank in Stealing if (but only if) you attempt to steal while stealthed. If you're not stealthed, obviously, your points in Stealth don't contribute to your thief score. Be warned that attempting to steal will break your stealth, even if you're succcesful. Further, you need Stealing IV to attempt to steal in combat.
Oh, one more thing: T is randomized to within 80-120% of the value above before being compared to V. That's why stealing is non-deterministic.
The formula for victim score is:
V = [mental resistance] + [creature rank bonus] + 2 * [victim's level - thief level (this can be negative)] + 10 (if thief or victim are in combat)
The rank bonus is 0-5 for white creatures, 10 for yellows, 20 for bosses, and 40 for elite bosses.
AN EXAMPLE
Let's go through an example to see how this works in practice. Suppose we are a level 12 model citizen trying to steal from a level 10 yellow NPC with 20 mental resistance outside combat. The victim's score is:
V = 20 + 10 + 2 * (10-12) = 26
In order to guarantee success, we would need a thief score of 27 / 0.8 = 34 (rounded up to the nearest integer). How can we obtain a T of 34? There are many ways:
* Stealing I, cunning 39
* Stealing I, Stealth I, cunning 34
* Stealing I, Stealth III, cunning 24
* Stealing IV, cunning 24
Etc. You can run through some hypotheticals yourself to see how this works. I don't know the stats of every NPC, so please don't ask me how much mental resistance the Reverend Mother has (you monster).
III: LOCKPICKING
This information comes from placeable_h.nss and GetDisableDeviceLevel() in core_h.nss.
Whenever you attempt to unlock a chest or door, the game calculates a lockpicking score (L) and compares it to the lock difficulty (D). If L >= D, the attempt is a success; otherwise it fails. Unlike stealing, there is no random element in lockpicking.
The lockpicking score is simple to compute:
L = (cunning - 10) + 10 * [lockpicking rank]
Your lockpicking rank is the number of points you have in the Deft Hands tree. If you have Deft Hands alone, your rank is 1; if you have Device Mastery, your rank is 4. As you can see, each point in the Deft Hands/lockpicking tree is worth 10 points of cunning. Notice that you can actually open locks without any points in the lockpicking tree if your cunning is high enough (I confirmed this in-game).
If you successfully pick a lock, you'll gain XP equal to D (with a minimum of 5). Thanks Sheffsteel for the observation.
Great! But how high does your lockpicking score have to be to pick every pickable lock in the game? Unfortunately I don't have the time or know-how to inspect every lock in the toolset to find a maximum value for D. However, there is a big hint in traps.xls, which contains a sheet called lock_difficulty with the following table:
1 Auto Success
10 Simple
20 Very Easy
30 Easy
40 Medium
50 Hard
60 Very Hard
10000 Impossible
So I would tentatively suggest that you need a lockpicking score of 60 to pick every lock that can be picked. You can achieve a lockpicking score of 60 by getting Device Mastery + 30 cunning, or Mech. Expertise + 40 cunning, etc. Of course, some locks will still require keys or event triggers to open.
Some people have finished the game with a lockpicking score of 60 and said this was enough to open everything. One person on the old forums said he was unable to open a chest with a lockpicking score of 64, but I don't know the circumstances. I would appreciate feedback from more people about whether 60 is enough for everything.
IV: TRAPS
This information comes from sys_traps_h.nss, placeable_h.nss, and GetDisableDeviceLevel() in core_h.nss.
Trap disarming is just like lockpicking; the game calculates a disarm score using the exact same formula it uses to calculate your lockpicking score. It then compares this to the trap's disarm difficulty. If your disarm score >= the disarm difficulty, the trap is succesfully disarmed; otherwise it is not. There's one exception: you can always succesfully disarm your own traps.
As with lockpicking, if you succesfully disarm a trap you'll gain XP equal to the trap's disarm difficulty (down to a minimum of 5).
Trap detection works like this: the game periodically checks for hidden enemy traps within a spherical volume with radius 10m + 1m per lockpicking rank (at Device Mastery this is a 14m radius). Note that the trap-making skill apparently does NOT increase your detection radius, despite what the tooltip says. For each hidden enemy trap within that volume, the game checks the player's disarm score (see paragraph above for how to calculate it) against the trap's detection difficulty. If this score >= the trap's detection difficulty, the player detects it; otherwise the player does not.
Minor note: for detection purposes only, the player gets a +10 bonus to his disarm score if he is under the effect EFFECT_TYPE_TRAP_DETECTION_BONUS. I have no idea what, if anything, grants this effect. It doesn't seem like the trap-making skills or lockpicking talents grant this effect, nor do any other spells or talents. Maybe it's just unused.
Notice that a trap's detection difficulty and disarm difficulty are different variables. This explains why you can sometimes detect a trap but fail to disarm it.
How difficult are traps to disarm or detect? Again, traps.xls gives us a hint. It has a sheet called trap_difficulty that contains a table identical to the one copied above for locks. So I would tentatively say that a disarm/lockpicking score of 60 will enable you to detect and disarm every trap that can be detected and disarmed. Again, player feedback would be appreciated.
V: COERCION
The information here comes from UT_SkillCheck() in utility_h.nss. Credit goes to Codrus0 for finding it!
The coercion formula is simple to state. Every rank in Coercion gives you 25 "coercion points." Every point in cunning above 10 (for Persuade checks) or in strength above 10 (for intimidate checks) gives you 1 coercion point. The most difficult coercion checks require 100 coercion points to pass. Coercion checks are deterministic.
This means that Coercion 4 should be sufficient by itself to pass every Persuade or Intimidate check without any investment in cunning or strength. Coercion 3 is sufficient if you have at least 35 cunning or strength, as appropriate. And so on.
Modifié par Discobird, 21 novembre 2009 - 01:53 .
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thx for your work
