The Skill system in YAUGS is based upon a hierarchical tree system. Characters may purchase skills at any of the levels in the hierarchy, the cost of purchase depending upon the current level of the skill in question.
In addition to a hierarchy skills are grouped by their costs. The cheapest are basic skills, whilst the most expensive are complex skills.
Basic skills have no pre-requisites, which means they can be learnt by any character.
Typical basic skills are Reading (own language), Writing (own language), Athletics, Swimming, and most combat skills.
Advanced skills may or may not have pre-requisites meaning they can only be learnt by a character that has the pre-requisite skill to the required level. Some Advanced skills have more than 1 pre-requisite skill. Having high levels in the pre-requisite skills may add a bonus to executing the Advanced skill.
Typical Advanced skills are sciences, engineering skills, and knowledge skills.
Complex skills all have multiple pre-requisites, generally of Advanced skills. Most are skills that are only available in a High Tech environment.
Typical Complex skills are Starship Gunnary, Pilot - Starship, Navigate - Starship.
YAUGS groups skills into a hierarchy of Primary(root), Secondary(branch), Tertiary(leaf), and optionally Quaternary(vein) skills. Each level in the hierarchy increases the level of specialization with in the skill group. At each level a skill may be Basic, Advanced, or Complex, and may have Basic, Advanced, or Complex children. However, most Complex Skills have Complex children. There are certain skills where there is no Primary Skill and some where there are neither Primary or Secondary. In these cases the skills must be bought directly.
For example, the skill Melee weapons is a primary skill and covers any weapon that may be wielded in the hand to stab, slash, crush, or bash an opponent. Beneath this root skill are the branches such as sword, axe, blunt, polearm, etc. Each of these is a secondary skill. Each secondary skill may be further sub-divided, for example sword may be divided into short, broard, long, bastard, etc
Primary skills are the root of the tree and are wide ranging skills with virtually no specialization. Typical Primary skills are Melee Weapons, Ranged Weapons, Science, Technology, Espionage, Survival.
Secondary skills add a level of specialization within a particular area, for example Chemistry, Physics, and Biology are all Secondary level skills within the Science Primary group.
Tertiary level skills add a further level of refinement and in most cases are the most specialized form of the skill, unless the optional Quaternary level is being used. Typical Tertiary level skills are Genetics, Virology, Industrial Chemistry, Organic Chemistry, Astro-Physics, Nuclear Physics.
A few Tertiary skills can be further sub-divided into specific skills. For example the Single Edge Sword skill can be further sub-divided into Falcion, Tulwar (the wide Arabian sword), Cutlass, Sabre, Katana, Wakasashi, etc.
The option to use this further sub-division is down to the GM.
Skills range in level from zero - no skill to 20 - the undisputed expert. The level of a skill determines the chance of success with that skill. At levels 1-5 each level adds 10% to the chance of success. At levels 6-10 each level adds 7% to the chance of success. At levels 11-20 each level adds 5% to the chance of success. This yields a maximum possible chance of success of 135% without additional modifiers
Skills are purchased with character points at any level primary, secondary, tertiary, quaternary, and the points spent flow down to each level below.
The cost to buy a skill at a given level depends on its type, Basic, Advanced, Complex, and the level of skill being purchased. For Basic skills each level costs a number of points equal to 10 times the level being purchased. For Advanced skills each level costs a number of points equal to 15 times the level being purchased and for Complex skills each level costs a number of points equal to 25 times the level being purchased.
Thus, to purchase melee weapons at level 3 costs, 60 points ((1+2+3)=6 x 10).
The advantage to purchasing skills at the root level is that these point then flow down. Thus, having purchased Melee weapons at level 3, 60 points are now available to spend on secondary skills within the Melee weapons category. The restriction is that no more than 50% of the points may be spent on a single sub skill, thus with 60 points I could purchase level 2 skills in blades and polearm, each costing 30 points. These points then flow down into tertiary skills, thus my 30 points in blades would buy me level 1 skills in single edge sword, dagger, and bastard-sword. With only 10 points available in single edge specializing in a specific sword type, assuming the option is available would not be possible.
The actual level of use with any skill is the sum of the levels of itself and its parents/grand parents. Thus a flail, defaults to melee weapons, would be used at skill level 3, a broad sword, defaults to Bladed Weapon, would be used at level 5, and a single edge sword would be used at level 6.