FeatureDefinition

FeatureDefinition is a data-driven construct used in role-playing game systems to describe a character feature that can be earned, learned, or selected. It acts as a template that consolidates all metadata and behavior needed to apply the feature to a character, including its source (class, feat, racial trait, or background), prerequisites or level gating, and the concrete effects on statistics, abilities, or resources.

A FeatureDefinition typically includes a unique identifier, a display name, and a textual description, along with categorization data that indicates whether it is a class feature, a feat, a proficiency, a power, or a passive ability. It records selection rules and prerequisites (for example, required level or other features) and one or more effects that are applied when the feature is granted. The effects may modify ability scores, grant proficiencies, add actions, restore resources, or alter other rule elements.

In practice, a game engine or character progression subsystem reads FeatureDefinition entries to assemble a character’s feature set, present them in the user interface, and enforce rules during play. Definitions are commonly stored in data files such as JSON or YAML, or in database records, and are often versioned to support updates or patches. They are designed to be composable, allowing complex features to reference other definitions or to compose multiple effect blocks.

See also: related definitions such as FeatureDefinitionPower, FeatureDefinitionProficiency, and FeatureDefinitionAbility.