Rolls are checks in the game, where your success at an activity (Action, Ability, Spell) is determined.
They either are a simple chance expressed in a percentile or a check of an Attribute/Skill versus a certain number as a threshold for success.
With Contested Rolls, the threshold is what your target manages to put up with his or her own Roll of an Attribute/Skill.
This is simply a check against a certain percentile. For example, you have the Ability to Run a Potentially Crippling Course at the Groundskeepers Office (it's automatically added at the beginning).
Here, you don't need to roll for the 3 Step Expansion to Running, but for the permanent Expansion of your Fitness Attribute. The Chance is set at 10%, but can be modified.
After some Random Events, your "Results of the Day" report may list any entry that your Chance of Success is raised for 33% (or 5%) for some time. If you take the Running Course after that, you will notice a much higher rate of success getting that Fitness Expansion.
Rolls against a fixed value
Most checks for success involve a Roll given in the format: Attribute/Skill v. (number), which may refer to a Parent Skill or a Subskill. The Ability "Try to Solve the Block Puzzle" you get automatically is set as Luck/Puzzles Roll v. 17 (which is quite steep).
While the method of the game's engine at working out the results are not fully understood, there are some hard facts:
- The actual Roll determines only the factor at which the involved Attribute is added to the Skill value. That factor is certainly not Integer but a fraction, which may range from "zero" to (almost) double the Attribute.
- While it is unknown if the factor can actually be a real "zero", it is likely that the randomly determined factor can be so low that it is rounded down to zero or a Chance of Failure will cancel it out. When your Attribute and Skill match the difficulty of the roll, your option will be blue (good Chance of Success).
- Achieving a roll at double the value of the Attribute is next to impossible.
You pit your roll Attribute/Skill against your opponents Roll. The latter may use the same pairing of attributes and skill, or some other as indicated in the description.
Chance of Failure/Chance of Success
A positive Chance of Success will add to your Roll of Attribute/Skill or Percentile Rolls.
By the description, this might be a hidden derived Attribute governed by the Luck Attribute.
It is not known, whether Chance of Failure is just subtracted from Chance of Success or if they are totally different values with Chance of Failure superseding an otherwise successful Roll. Examples include Paint a Fog (Action) and Prepare (Action)).
Note : That might be the case, as "Before Chance even Fate must bow." (Fritz Leiber - Swords of Lankhmar)
Rerolls make you roll twice or thrice, with Reroll: Best taking the better result of either normal or percentile Rolls, and Reroll: Worst taking the lower result.
Rerolls either affect your Rolls using a certain or random Skill/Subskill or they affect particular or all of your Actions, Abilities, or Spells. Creative Approach and Sheary's Help grant re-rolls to everything for a small period of time. Seven Favors grants 3 rerolls to all seven attribute checks.
- Add random Subskill Reroll: Worst (e.g. Icy Breath (Ability))