Editing Unknown Armies (section)

== System ==

Unknown Armies is based on a '''percentile''' system where you must roll underneath the relevant attribute for the situation.  You are more successful the closer you are to your ability score without going over it; for example, rolling a 21 with a skill of 25 is better than rolling a 12. A '''matched success''' is a roll underneath the attribute with two matching digits, for example, 11 or 22, and it represents unusual success. It also works the other way: a matched failure will be unusually terrible. A '''crit''', a roll of exactly 01, gives the best possible outcome, while a roll of 00 is a '''fumble''': the worst possible outcome. There are also shifted rolls, which add or subtract a skill modifier based on the situation.

The UA system addresses the idea that more stressful situations will make performing tasks harder. There are three "types" of rolls, depending on how stressful the situation is: minor, significant, and major. For '''minor''' skill checks, when there is little risk or ample time, you automatically succeed if you have 15% or higher in the skill. For '''significant''' skill checks, when there is some amount of pressure, you get a strong success if you roll under your relevant skill and a weak success if you roll under the relevant stat. For '''major''' skill checks, when the situation is very stressful and your performance really matters, you must roll under your skill to succeed. All combat checks are major.

For an unskilled minor or significant check, your stat takes a -30% shift. For an unskilled major check, you can roll a Hail Mary, which will only succeed with a matched success or a crit.