Skill based

A Skill-based system is a method of mechanically representing entities in an RPG that is an alternative to the more traditional class-based system. In the skill-based system, concepts such as a character's "level" are typically non-existent, and the character's abilities are governed by their points or ranks in given skills as opposed to being based on their character level. Rather than a set amount of experience resulting in the gain of a level and all the associated benefits that brings, skill-based systems usually involve an improvement mechanic where characters spend earned experience to improve a skill or attribute, or gain a specific special ability.

More complex skill-based systems usually also include more basic physical and mental characteristics of the characters (such as measure of how strong, agile, or intelligent they are), which are used in conjunction with the learned skills to determine a character's overall ability at some task. It is normally possible for these attributes to be improved by the expenditure of experience in the same way as skills (although typically at greater expense, as the benefits gained from an improved attribute tend to apply to a lot more potential tasks or situations than a more specific skill). However, this is not always the case, especially in very simple systems designed to pick up an play quickly, where the entire mechanical representation of a character may be a small list of skills (or equivalent, such as the Cliches in Risus) and relative proficiency in each.

Skill-based systems are generally considered to produce more realistic individuals than level-based systems, since achieving a high degree of proficiency in a given skill does not also necessitate improvement in many other, potentially unrelated areas. Consider Dungeons and Dragons, where in 4E a character's competency in the application of any given skill is a function of their level, their related ability score, and whether or not they are considered "trained" with the skill (a flat +5 bonus to rolls). Assuming they are already "trained", the primary methods of increasing their bonus with a given skill are to improve the associated ability score or to gain a level, both of which will also improve a character's skills in a wide variety of other areas. In a skill-based system such as World of Darkness, however, a character who wishes to become better at a specific skill merely spends the experience necessary to improve that skill without affecting any of their other abilities, allowing for true specialisation.

Notable skill-based systems include:

• World of Darkness - uses a 0-5 "dots" representation of skills and attributes, where 0 is completely unskilled or inept and 5 represents extreme expertise or capability
• Dark Heresy - although characters do have an assigned Career (basically a class) and ranks (sort-of levels), their only important mechanical purpose is to define which skills and talents are available to a character to spend their experience on, although this is much more restrictive than most skill-based systems
• Risus - characters are defined entirely by "Cliches", such as "Viking", "Wizard", or "Bumbling Hero", with a numerical indication of their competency (or incompetency) at tasks that would fall under the purview of that cliche