Rolling Dice: Use two ten-sided dice to play the game. Usually these are read as percentiles from 01-00 (100), with one die as the tens digit and one die as the ones digit. A 0 in the tens digit counts as a leading zero (0 and 8 is 08 = 8). A 0 in the ones digit counts as a trailing zero (8 and 0 = 80). Sometimes they are added together, in which case the 0 counts as ten (8 + 0 = 18). Sometimes a single die is rolled by itself, in which case the 0 also counts as ten (0 = 10).
Character Stats and Skills: Humans have stats (Body, Speed, Mind, Soul) and skills (Horseback Riding, Greek History, Safecracking), all of which can range between 1% - 99%. Each skill is tied to a single appropriate stat. To take an action during the game, you use the skill and roll the dice. If you do not have the appropriate skill, the game master may allow you to roll against the relevant stat instead--but you will not be able to succeed nearly as well as you would with the right skill, or it may take you much longer, or the game master may impose some other penalty.
Minor Skill Checks: In relaxed situations where you have plenty of time and are not at risk, you automatically succeed in any skill that you have at 15% or higher. The game master may ask you to roll anyway just to see how long it takes you or how good a job you do, or to see if you get any matches, crits, or fumbles (see below). If you do not have a suitable skill, you may attempt a minor skill check by rolling against the appropriate stat instead to just barely squeak by the task (a weak success); for this roll, your stat is reduced by 30.
Significant Skill Checks: In situations where there is uncertainty but little actual risk, you succeed strongly if you roll equal to or under your skill level and you succeed weakly if you roll above your skill level but equal to or under your related stat level. If you do not have a suitable skill, you may attempt a significant skill check by rolling against the appropriate stat instead for a weak success; for this roll, your stat is reduced by 30.
Major Skill Checks: In tense situations where time is important and/or you are at risk, such as in combat, you only succeed if you roll equal to or under your skill level. If you do not have a suitable skill, you may attempt a major skill check by rolling against the appropriate stat instead and hoping for a Hail Mary: only matched successes and criticals (see below) succeed; your stat is not reduced for a Hail Mary roll.
When to Roll: The GM always decides what rank of skill check to request and how to interpret it. He or she may be aware of factors you do not know about.
What to Roll: Besides rolling equal to or under your skill or stat level to achieve success, the number you roll has other effects. Your goal is to roll as high as you can without going over your skill. The closer your roll is to your skill level, the better you do. If you have a skill at 46%, a roll of 43 is better than a roll of 04.
Minimum Rolls: The game master may require you to roll a certain number or higher, as well as below your skill or stat. To shoot someone in the leg, you might have to roll under your skill level with a minimum roll of 30. If your skill is lower than the difficulty, you cannot perform the action.
Matched Rolls: A match is when both dice come up with the same number, such as 11, 66, or 44. This makes the action you are attempting more dramatic, but whether that added effect is good or bad depends on whether the roll was a success or a failure. A matched successful roll is unusually good, but a matched failed roll is unusually bad. Most of the time, the game master interprets what additional effects this triggers. However, some actions in the game have specific effects keyed to matched rolls--these are called Cherries.
Fumble Rolls: A fumble is when you roll double zeroes (00) and it means the worst possible outcome occurs--short of death. Even if you somehow have a skill or trait at 100%, rolling a 00 is still a fumble.
Crit Rolls: A crit is when you roll a zero-one (01) and it means the best possible outcome occurs. It does not mean you can succeed at an impossible task, such as picking up a skyscraper and throwing it across town. A crit supercedes even a difficult roll.
Flip-Flop Rolls: In some situations or with some skills, you may be allowed to flip-flop a roll. This means you have the option of switching the dice. If you rolled a 91 and you can flip-flop that roll, you could make it a 19 instead if it's better for you.
Shifted Rolls: A shift is a modifier applied to your skill number before you make the roll. If you had a Greek History skill of 56% and for some reason a -30% shift was applied, your skill would be 26% instead. Shifts are usually temporary, and might be applied because of wounds, difficult environments, or magickal effects.
Hunch Rolls: A hunch is a percentile roll you get to make and then set aside to use for the next time you need a skill check. In other words, you know what your next roll is going to be and can act accordingly, using it up on something unimportant if it's bad or trying to save it for something important if it's good. Hunches are awarded by the game master in some situations for magickal or mundane reasons. Note that you cannot always control when you make a roll, so don't try to hang on to a good hunch too long or you may lose it on a meaningless action.