Rules

This page preserves the useful context for the older C++ rules and modifier system. New rules authoring work is moving toward Smalls and propsets so rule data can be authored, tested, and embedded without growing hardcoded C++ policy.

Original Goals

• Rules should be overridable, expandable, or removable through configuration or programmatic registration.
• Rules should be queryable for a concrete situation, such as the modifiers affecting one creature attacking one target with one weapon.
• Rule constants should avoid being permanently tied to 2da row numbers when a ruleset-specific mapping is the real policy.

Useful Definitions

Attribute: A feature inherent to an object, such as creature ability scores.

Profile: A ruleset-specific layer that decouples rule values from the core rules service.

Type: A typed rule value, such as an armor class category. The rule system defines the type and invalid value; profiles define valid values.

Flag: A compact flag built from a rule type.

Modifiers

The older modifier system is built on integer, floating-point, string, and function inputs stored in the global rules service. Modifier resolution calls a registered callback or uses helpers such as sum/max resolution for common cases.

auto mod = nw::make_modifier(
    mod_type_hitpoints,
    20,
    "dnd-3.0-epic-toughness",
    nw::ModifierSource::feat,
    { nw::qualifier_feat(nwn1::feat_epic_toughness_1) });

nw::kernel::rules().modifiers.add(mod);

This remains useful compatibility context, especially for existing NWN profile behavior. It should not be treated as the only rules direction for new authored game systems.