The Hotness
Games|People|Company
Tomb of Annihilation
The Streets of Marienburg
Legacy of Dragonholt
Superbabes: The Femforce Role-Playing Game
Maze of the Blue Medusa
Tales from the Loop
Starfinder Core Rulebook
Dungeon Master's Screen, Reincarnated
Tome of Adventure Design
The 9Qs
Barrowmaze Complete
Adventures in Middle-earth Player's Guide
Robert E. Howard's Conan: Adventures in an Age Undreamed Of
RPG Geek Random Tables
The Tortle Package
Borg Cube Collector's Edition Box
White Star: Galaxy Edition
Warhammer Fantasy Roleplay
The Ruins of Undermountain
Twilight Imperium: The Role-Playing Game
ASE1: Anomalous Subsurface Environment: City of Denethix and Dungeon Level 1
Dwarven Vengeance
The One Ring Roleplaying Game
DDEX1-01: Defiance in Phlan
Star Trek Adventures Core Book
Reign of Terror
Star Trek Adventures GM Screen
Players Handbook (AD&D 1e)
Shadows over Bögenhafen
Plundered Vaults
Dogs in the Vineyard
T1-4: The Temple of Elemental Evil
Player's Handbook (AD&D 2e)
Trail of Cthulhu
Dice
The Arcanum (First and Second Editions)
2.0: Spires of Altdorf
Horror on the Orient Express
Fields of Ruin
Player's Handbook (D&D 3e)
Chrome Book
The Night of Dissolution
The Forge of Fury
Castle Keeper's Guide
Loot: A Field Guide
Gamma World Roleplaying Game
Dungeon Crawl Classics Role Playing Game
Star Wars: Edge of the Empire Beginner Game
Fate Core System
Castle of the Mad Archmage Adventure Book
Recommend
25 
 Thumb up
 Hide
8 Posts

Storyteller» Forums » Rules

Subject: Storyteller System flaws rss

Your Tags: Add tags
Popular Tags: probability [+] dice_probability [+] dice_mechanic [+] [View All]
He went overloading on testing and coding and his name was
United Kingdom
Redhill
Surrey
flag msg tools
admin
designer
Support comes in many forms: community involvement, forum posts, submitting data, running PbF games, word-of-mouth advertising, financial donations... All these are vital to this site, and you have my sincere thanks for participating in any of them.
badge
Currently: planning.
Avatar
mbmbmbmbmb
I would like to document some interesting flaws in the core action resolution mechanic in the Storyteller system. If you are familiar with this system, you can skip the introductory background that explains how it works.


Background

Characters have a number of Attributes and Abilities each of which is rated from 0 to 5. 2 is an average human score. 5 is the highest human potential. Some supernatural powers may raise the values beyond this maximum.

An action is typically tested by the appropriate combination of attribute and ability, adding the values together to calculate the size of the dice pool. This many ten-sided dice (with values read as 1 to 10) are rolled against a target difficulty. Each individual die rolling equal to or higher than the difficulty counts as a success. Each individual die rolling a 1 deducts one of these successes. Rolling more 1s than successes is called a botch; rolling a net total of 0 successes is a failure; a positive amount of successes is a success, with the number of net successes determining the degree of success (typically on a scale of 1 to 5).

Note that when the Storyteller system was revised in 1998, the definition of a botch changed subtly: a botch would only result if there was at least one 1 rolled, and no successes at all (as opposed to a greater number of 1s than successes).

So usually dice pool sizes range from one to ten dice. Even with supernatural powers, it is unusual that more than twenty dice are rolled.

A standard target difficulty number is 6, although the difficulty can range from 2 to 10.


Flaw: Difficulty 2

Any individual die roll can only be a success (+1) or a botch (-1). This means that when rolling an odd number of dice, it is impossible to fail; only to succeed or botch. But when rolling an even number of dice, one can succeed, fail, or botch.

This skews the probability distribution in odd ways:


Flaw: Probability of Botching
Affected core rules:
Vampire: The Masquerade (1st Edition) (1991)
Werewolf: The Apocalypse (1st Edition) (1991)
Mage: The Ascension (1st Edition) (1993)
Wraith: The Oblivion (1st Edition) (1994)
Changeling: The Dreaming (1st Edition) (1995)
Vampire: The Masquerade (2nd Edition) (1992)
Werewolf: The Apocalypse (2nd Edition) (1994)
Mage: The Ascension (2nd Edition) (1995)
Wraith: The Oblivion (2nd Edition) (1996)
Changeling: The Dreaming (2nd Edition) (1997)
Vampire: The Dark Ages (1996)
Werewolf: The Wild West (1997)
Mage: The Sorcerers Crusade (1998)
Note that this flaw was fixed in the system starting
with the revised edition of Vampire: The Masquerade,
and the following core rules are all unaffected:

Vampire: The Masquerade (Revised Edition) (1998)
Werewolf: The Apocalypse (2nd Edition) (2000)
Mage: The Ascension (Revised Edition) (2000)
Dark Ages: Vampire (2002)
Dark Ages Basic Rules (2004)
Hunter: The Reckoning (1999)
Demon: The Fallen (2002)
Orpheus (2003)
Vampire: The Masquerade (20th Anniversary Edition) (2011)
Werewolf: The Apocalypse (20th Anniversary Edition) (2012)
It would be a reasonable assumption to make that as a character improves in their ability to perform a particular task, that the chance of a critical failure (botch) should decrease; or at least should not increase. However this is not always the case with the system as written: for a fixed target difficulty, the probability of botching can sometimes increase as your dice pool increases.

The specific ranges where this flaw occurs are...

Difficulty 2: the probability of botching when rolling an odd number of dice is higher than when rolling one less die.

Difficulty 2: the probability of botching when rolling 3 dice is higher than when rolling 2 dice.

Difficulty 7: the probability of botching when rolling 2 or 3 dice is higher than when rolling 1 die.

Difficulty 8: the probability of botching when rolling 2 to 8 dice is higher than when rolling 1 die; the probability of botching when rolling 3 to 4 dice is higher than when rolling 2 dice.

Difficulty 9: the probability of botching when rolling 2 to 36 dice is higher than when rolling 1 die; the probability of botching when rolling 3 to 19 dice is higher than when rolling 2 dice; the probability of botching when rolling 4 to 12 dice is higher than when rolling 3 dice; the probability of botching when rolling 5 to 9 dice is higher than when rolling 4 dice; the probability of botching when rolling 6 to 7 dice is higher than when rolling 5 dice.

Difficulty 10: the probability of botching always increases, the more dice that you roll.

As mentioned above, the revised edition of the rules starting from 1998 fixed this bug. Instead, botches could only be rolled if there was at least one 1 rolled, and no successes at all (as opposed to a greater number of 1s than successes). This gave a maximum probability of botching of 10% for a dice pool of 1, with a reduced probability of botching as the dice pool increased. Probabilities of success were completely unaffected.

This was a fine solution, and completely fixed the problem (after only seven years of product sales).



Probability Distributions

Here are graphs for all difficulties; open them up for a larger view. The probabilities are also listed in a comment to each image, to 0.1%.
Difficulty 2:

Difficulty 5:

Difficulty 8:
Difficulty 3:

Difficulty 6:

Difficulty 9:
Difficulty 4:

Difficulty 7:

Difficulty 10:

19 
 Thumb up
3.05
 tip
 Hide
  • [+] Dice rolls
Hans Messersmith
Canada
Hamilton
Ontario
flag msg tools
admin
designer
With your head held high and your scarlet lies You came down to me from the open skies It's either real or it's a dream There's nothing that is in between
badge
Twilight, I only meant to stay awhile Twilight, I gave you time to steal my mind Away from me.
Avatar
mbmbmbmbmb
Nice article Stelio.

Here is another article covering similar territory...

http://www.scribd.com/doc/46230301/d10-Probability

It is of interest mostly because of the formulas it derives.
6 
 Thumb up
 tip
 Hide
  • [+] Dice rolls
フィル
Australia
Ashfield
NSW
flag msg tools
designer
badge
Pushing a lesbian old growth union-approved agenda since '94.
Avatar
mbmbmbmbmb
Strange that some game designers don't do the maths as a matter of course. Not everyone's a mathematician, but hopefully there's a friend of a friend or an excel template or something to help with probability.
5 
 Thumb up
 tip
 Hide
  • [+] Dice rolls
In addition to the revised Vampire probabilities (when you get around to them), I'd also be interested in a comparison to nWoD.
3 
 Thumb up
 tip
 Hide
  • [+] Dice rolls
He went overloading on testing and coding and his name was
United Kingdom
Redhill
Surrey
flag msg tools
admin
designer
Support comes in many forms: community involvement, forum posts, submitting data, running PbF games, word-of-mouth advertising, financial donations... All these are vital to this site, and you have my sincere thanks for participating in any of them.
badge
Currently: planning.
Avatar
mbmbmbmbmb
dysjunct wrote:
In addition to the revised Vampire probabilities (when you get around to them), I'd also be interested in a comparison to nWoD.

Article, graphs, and tabulated probabilities all updated to reflect the improvements introduced by the revised edition of the rules.

So... what are the full details of the nWoD mechanics?
7 
 Thumb up
 tip
 Hide
  • [+] Dice rolls
I'm no expert, I've only played nWoD once, and I'm in my cups, but I think it is:

- basically the same, dots etc.
- however target numbers are fixed. 8+ is always a success, 10s count as successes and get rerolled, with exploding possible.
- number of successes is always degree of success, using the standard 1=marginal, 3=complete, etc.
- situational difficulty substracts dice from the pool.
- botching is only possible if lack of skill and/or difficulty reduces your pool to one die or fewer. In that case, you still get to roll a die, but a one is a botch.

Please correct, nWoD fans!
2 
 Thumb up
 tip
 Hide
  • [+] Dice rolls
Samuel Sol
Brazil
São Paulo
SP
flag msg tools
admin
All engines full to awesome land!
badge
*tap* *tap* Is this thing on?
Avatar
mbmbmbmbmb
This sounds a lot like Scion and Exalted, so I think it is correct for nWoD
1 
 Thumb up
 tip
 Hide
  • [+] Dice rolls
Blue Tyson
Australia
SA
flag msg tools
badge
Avatar
mbmbmbmbmb
That always annoyed me, too. I never played the new version, though.
 
 Thumb up
 tip
 Hide
  • [+] Dice rolls
Front Page | Welcome | Contact | Privacy Policy | Terms of Service | Advertise | Support BGG | Feeds RSS
Geekdo, BoardGameGeek, the Geekdo logo, and the BoardGameGeek logo are trademarks of BoardGameGeek, LLC.