TDRS (Trait-Driven Relationship System) is a Unity package for modeling dynamic character relationships in RPGs, simulation games, visual novels, and adventure games. Designers can model character personalities, emotions, affinities, and relationship statuses. They can also define various social events that NPCs can respond to, given their relationships with the party(s) involved. TDRS aims to empower designers to create engaging, relationship-driven gameplay where the immediate and second-order effects of various social interactions drive NPC decision-making and narrative progression.

Designers can model NPC personalities, emotions, relationship statuses, and interpersonal affinities using combinations of numerical stats and traits. Traits are the driving force of TDRS, as its name implies. They are tags of information attached to NPCs and relationships that provide additional semantic information and may apply various effects or social rules that change how a character treats another.