1 - The Dice

At its core, this game system is built around three six-sided dice, typically rolled and added together. Such a roll is called a check. A base target number is typically 10, adjusted with modifiers, which may come from stats, skills, gear, and/or situational modifiers. With no modifiers, a roll of 10 or more on 3d6 has a 62.5% chance of success. Because of the probability of 3d6 dice rolls, the most likely combination is a 10 or 11 (they have equal chances), and the further lower or higher the number, the less probable the result.

Target numbers are calculated by adding (or subtracting for negative) modifiers to a target of 10, then rolling a check (3d6). If the dice roll equals or exceeds the target, the check is a success, otherwise (for rolls less than the target) it is a failure. The degree to which a success or failure is rolled can have an impact on the results. Each time a check is made, the person making the check must announce their results in the following way. If a total roll is equal to the target number, that is a Success of zero, and represents the bare minimum success. If the roll exceeds the target number, that is a Success of [number], with the number being how much above was rolled. For example, if a target was 12 and the roll was 14, this would be announced as a Success of Two (meaning the dice rolled 2 over the target number). For failures, the reverse is true. So, if a target was 12, and an 11 was rolled, that would be a Failure of One, while a roll of 7 against the same target would be a Failure of Five.

Rounding down: sometimes you have to divide a bonus by a fraction, such as half (1/2). When ever you end up with a fraction, always round down to the next whole number.

Criticals and Blunders: a natural 16, 17, or 18 has a combined probability of only 4.6%, as does a natural 3, 4, or 5. These rolls rarely happen as a result. If a natural 16, 17, or 18 is rolled, this is called a critical. If a natural 3, 4, or 5 is rolled, this is called a blunder. A critical gets a bonus to the roll, allowing higher totals than is possible on a 3d6 (18 maximum, 3 minimum), and vice versa for blunders (the final result of the blunder may be a negative number). Depending on the critical/blunder, roll additional dice and add them to the result.

Natural 18 = +3d6
Natural 17 = +2d6
Natural 16 = +1d6
Natural 5 = -1d6
Natural 4 = -2d6
Natural 3 = -3d6

Chaos: when rolling a check, if three dice roll the same number, such as three twos or three sixes, this triggers a chaos result - something chaotic has happened and the GM must roll again to determine the chaos result. Slightly less than 2% of rolls will have chaos effects, so they are rare - the GM should use such an opportunity to add a memorable, chaotic complication to the action. To check the chaos result, the GM rolls 3d6: high is beneficial, low is harmful, determined by the GM. Possibly compare to 10, halving difference, and use as a temporary modifier for one round. Note that the chances of a chaos result increase with Superior or Inferior checks (see below), as only three dice need to hit the same number.

Superior and Inferior Checks

Sometimes the odds are stacked for or against your check, depending on the circumstances. For example, perhaps you are using a well-crafted weapon, or a shoddy one. Perhaps there are elements in the environment that help or hinder your actions. For minor modifiers (such as a well balanced weapon or slightly favorable circumstances), a simple plus or minus modifier to the target would suffice, but more extreme cases (say anything that would require more than plus or minus 4 modifier) require a Superior or Inferior Check.

For such checks, extra dice are added to the base roll of 3d6, then either the best or worst three dice are used to tally the result. Superior checks take the highest three, while inferior checks take the lowest three. The more extreme a situation, the more dice added. For example, sneaking up to someone and attacking them when they don't notice you may result in a Superior 1 Check (3d6+1d6, take 3 highest), while using a knife held to the throat of a helpless hostage may result in a Superior 2 Check (3d6+2d6, take 3 highest). Some counter examples: attacking a foe with a melee weapon while another is grappling you could result in an Inferior 1 Check (+1d6, take 3 lowest) while attempting to hit a target with a thrown knife that is two range categories beyond its listed range is an Inferior 2 Check (+2d6, take 3 lowest).

If multiple circumstances affect the odds, such as multiple superior or inferior modifiers, add like modifiers and subtract different ones. For example two circumstances that each give a Superior 1 Check would combine to give you a Superior 2 Check, while having a Superior 1 Check combined with an Inferior 2 Check would result in an Inferior 1 Check.

Below are the probabilities when rolling 4d6 and taking the lowest/highest three results. Notice that, for a Superior I Check, the bell curve is skewed towards the higher end, with the chance of a good critical increasing to 13% while a bad critical drops to 1.2%, while for an Inferior I Check the chance of a good critical is only 1.2% while a bad critical increases to 13% (Superior/Inferior are mirror opposites). This skewing of good/bad results across the bell curve increases with 5d6, 6d6, etc., as an example the odds of 5d6 is shown at the bottom (good crits for Superior 2 are nearly one in four, while bad crits are only three in a thousand. For Inferior 2, switch the good/bad odds). At Superior/Inferior 3 or more, the bad/good crit chance is effectively zero.

Below is a table of the probabilities of blunders from inferior checks (result of 3, 4, or 5), and the overall chance of a critical (range 16 to 18); as well as the probabilities for criticals from superior checks (result of 18, 17, or 16), and the overall chance of a blunder (range 18 to 16). Note for Superior/Inferior 3 or higher, the chances of a blunder/critical are effectively 0 (less than one in a thousand).