Gameplay tags
Hierarchical name tags (e.g. State.Debuff.Stunned) that label game objects and states without hard-coded enum types or a thicket of boolean flags.
The pattern was popularized by Unreal Engine's Gameplay Ability System. Instead of a bool isStunned or a brittle enum, objects carry a set of dot-separated hierarchical tags, and systems ask "does it have a tag under State.Debuff?". Logic decouples from code, becomes data-driven and designer-editable, and tags compose freely.
The cost is a registry and interning of strings to IDs — and that over-tagging quickly becomes its own mess. The core idea, labelling things with free hierarchical tags rather than types, shows up in many ECS-style and data-driven designs well beyond Unreal.