on a galactic scale
This article is a part of Project RPG.
To determine the success of a skill by difficulty roll means the character must roll against the Game Master. These are successes that do not necessarily have to do with the skill of another character, but rather in how hard the task is to do itself. In addition to the standard difficulty roll, the GM can modify many of these skills depending on the circumstance.
Skill difficulty rolls are a character's skill with bonuses compared to a GM's roll with a difficulty bonus. Difficulty bonuses are determined by how many Faculties or skills make up the prerequisite of that skill. For each prerequisite or Faculty of a skill the difficulty ranges by ten. For example, if a skill has 3 Faculties affecting it then the difficult range is from 1 to 30. The GM chooses a value within this range to add to his or her d10 roll. The value the GM chooses depends on the difficulty of the situation.
Frank wants to use his Resist Damage skill after he was struck. Since this is his ability to take the damage, it cannot be compared to another character, so a difficulty roll is in order. Since Endurance is the only Faculty or skill that supports this skill, the difficulty range is between 1 and 10. Frank was punched in the face, so compared to other kinds of damage, it is fairly easy to resist.
The GM chooses the value 2 on a scale of 1 to 10 for difficulty and adds that to his d10 roll. Frank rolls his skill by added all his bonuses to a d10 roll. If he beats the GM's roll then his damage is reduced by half. If Frank was using Demolitions (Targeting), the difficulty scale would be on a scale of 1 to 20, so a value of 2 would have been inconsequential.
A GM will find suggested difficulty values for various tasks in further descriptions of items, equipment, and vehicles. Ultimately, however, the difficulty value is entirely up to the GM, based on circumstances. Additionally a GM may choose to lower the bonus of the character based on circumstances. For instance, if a character was just slugged in the head with an iron bar he would likely not be able to figure out algebra as well as before.