Skill use basics

YAOSC, like all RPGs, is based on talking: the players describe what they want their characters to do and how they want them to do it, and the GM  describes the results. When there’s doubt about whether a given action will succeed or not, the fundamental tool is skills. Each player character has a list of skills with a rating for each, and rolls a check or challenge for the one most appropriate to the action being taken.

For checks, the GM chooses a die size based on the difficulty of the task. Dice scale according to the following progression: d2, d3, d4, d6, d8, d10, d12, d20, d30, d100. The default skill check die is a d6, although many other rolls will scale from a different base die size. Circumstances may change the difficulty by a number of “steps” up or down this scale; in many cases, players may choose their difficulty by setting the parameters of the task they want to accomplish. Other circumstances may add a bonus or penalty to the skill’s level.

Each skill has a level based on its default, the number of points the character has invested in improving it, and relevant situational modifiers. A check succeeds when the number rolled on the die is less than or equal to the skill level, and fails when it’s greater.

In contrast, in a skill challenge each character involved rolls two dice (2d10 is the default) and adds their skill level to the result. If one result is higher, it wins the challenge. Unlike checks, which are pass/fail, challenges can result in a tie.

Skill levels

Each skill begins at a default starting level. This may be zero – or some other numerical value – or it may be based on an attribute modifier. YAOSC will likely provide a list of “standard” starting levels, but these may be customized to fit the needs of a given setting or campaign.

Some skills may provide specific advantages at certain levels. For example, many combat skills allow trained warriors to perform special maneuvers. This compartmentalization is intended to make skills more interesting and useful than simply a series of increasingly big numbers. It is also intended to allow some activities (such as combat) to have a basic set of simple rules, for ease of use, with options for a deeper experience (and ways to make a character more distinct and special) available for unlocking as the players gain system mastery.

Skills can be trained, of course. Characters can increase their skills’ levels by investing points – some gained as a reward for increasing their character’s level; others gained during the course in play through in-world activities and events such as training or magical augmentation.

Each skill can be simple, normal, difficult, or forbidden – depending on the character’s race and class. (Like many details of the skill list, this factor can be adjusted to meet the needs of a given campaign, or ignored entirely.) Normal skills cost two points to increase by one level; simple skills, one point, and difficult skills, four. If a skill is forbidden to them, the character can’t invest points in it, and can’t use it at all unless it has a default level greater than zero.

Degrees of success (optional rule)

Sometimes you may want to know not just whether you succeeded or failed, but how well you succeeded or how hard you failed. In this case, for each four points by which the roll beat (or missed) the score it needed to succeed, the GM may count an extra degree of success or failure, and apply extra benefits or hindrances accordingly. For example, beating an opponent’s roll by 4-8 points (one degree) in a combat challenge may allow the victor to increase their damage die by a step, or failing a spellcasting check by 9-12 points (two degrees) may cause two extra problems for the character beyond simply failing to cast a spell.

Simulating dice you don’t have

Not everyone has a full set of polyhedral dice of all the above sizes. In cases where a limited selection of dice is available (and you can’t use an app or an online tool like this or this) here are some useful tricks:

• A d2 is essentially a coin flip; it can be simulated by choosing odds (1) or evens (2) on any other die.
• A d3 is half of d6, so you can simply roll d6 and round up.
• For a d4, you can roll a d6 twice. Each die will result in a low number (1-3) or high number (4-6). Read low+low as 1, low+high as 2, high+low as 3, and high+high as 4. Alternately, roll a d6 any number of times until it produces a result from 1 to 4.
• For a d8, use the same method as the d4 but add another roll. LLL=1, LLH=2, LHL=3, and so on in binary fashion.
• For a d10, roll 2d6. As above, the first d6 determines “low” or “high,” but in this case “low” is 1-5 and “high” is 6-10. The second die determines the value within those ranges, ignoring a result of “six” (because that would produce either 6 out of 1-5, or 11 out of 6-10, which is invalid).
• For a d12, roll 2d6 as above, but don’t ignore the “six” rolls – instead, your possible ranges of results for the second die are 1-6 and 7-12.
• For a d20, combine the d4 and d10 simulation methods.
• For a d30, use the d10 method, except that the first die produces six ranges (1-5, 6-10, 11-15, 16-20, 21-25, and 26-30) instead of simply “high” and “low.”
• For a d100, roll or simulate two d10s. The first produces the tens digit, and the second produces the ones digit. Count “00” as 100.

If all that seems a little too mathematical for you, then I sympathize, but you’re really going to have to get some dice.