GameplayTags Foundation (Unity)

A lightweight, hierarchy-aware tag system. Tags are dot-separated names ("Effects.Buff.Strength")
stored as hashed ulong values (xxHash3) — zero runtime string cost after registration. Hierarchy
is inferred from path segments and compiled to interval (Lft/Rgt) ranges, so ancestor checks
are O(1) range tests instead of transitive-closure lookups. Includes editor tooling (a
Project Settings > Gameplay Tags panel for managing tag databases) and Burst-safe snapshot/
interval-map APIs for use inside jobs.

Tier

Foundation — free, open source (Apache 2.0), this whole repo. The paid Toolkit tier
(Heathen.GameplayTagsToolkit: an Inspector-driven tag collection component, a condition-set
asset, and an event-trigger/display pair) lives at
Unity/ToolkitSource/Assets/Toolkits/com.heathen.gameplaytagstoolkit/ inside Heathen's private
SourceRepo (sponsor/enterprise access only — see that repo's own SKILL.md if you have access).
This Foundation is a complete, independent tag system on its own; the Toolkit only adds
higher-level, no-code components on top of it.

Up

`github.com/heathen-engineering/SourceRepo/SKILL.md`
— the ecosystem-level guide (what Heathen Engineering is, how products/tiers are organized across
engines). This repo has no local engine-level SKILL.md to link to instead, since it's a
standalone single-product repo, not part of that larger source tree.

Key namespaces / entry points

Namespace: Heathen.GameplayTags (runtime), Heathen.GameplayTags.Editor (editor-only: settings
provider, drawers, ITagSource/ITagVocabulary).

Type	Purpose
GameplayTag (readonly struct, wraps ulong)	A single tag. FromName(dotPath) / FromId(ulong); implicit conversions string ↔ GameplayTag ↔ ulong; IsAncestorOf(other), GetDescendants().
GameplayTagRegistry (static class)	Source of truth for what tags exist. RegisterDefaults/UnregisterDefaults, Hash, IsAncestor, GetDescendants, GetAllIds/GetAllNames, TryGetInterval, IntervalGeneration, GetNativeIntervalMap(Allocator) (Burst-safe).
GameplayTagCollection (managed class, ISerializationCallbackReceiver)	Per-entity tag container with stack-count semantics: AddTag/RemoveTag/Apply(tag, arithmetic, value), Contains/ContainsAll/ContainsAny/ContainsNone, Subscribe/Unsubscribe, GetSnapshot(Allocator) (Burst-safe), Changed event.
GameplayTagCondition	A single tag comparison (Exists/NotExists/Equal/Less/Greater/etc.) plus LogicOp (And/Or/Xor) for chaining. EvaluateAll(conditions, collection) does AND > OR > XOR precedence reduction.
GameplayTagOperation	Bundles a tag + GameplayTagArithmetic + value + optional GameplayTagCondition list so a mutation can be stored as data. ShouldApply/Apply(collection).
CompiledTagEntry, NativeDescendantsMap, NativeIntervalMap	Supporting types for the interval-encoded hierarchy and Burst job access (NativeDescendantsMap is obsolete — prefer interval range tests via NativeIntervalMap).
GameplayTagArithmetic (enum)	Set, Add, Sub, Mul, Div, Min, Max.
GameplayTagComparisonOp / GameplayTagLogicOp (enums)	Condition comparisons / chain logic.
GameplayTagsSubsystem ([Subsystem(SubsystemScope.Global)])	Owns registry-reset timing at framework boot (Game-Framework Subsystem, not a MonoBehaviour).
ITagSource / ITagVocabulary (Editor)	Provenance/autocomplete interfaces other tools implement to surface their own authored tags in the Gameplay Tags settings panel.

Tag databases are GameplayTagsData ScriptableObject assets, authored/managed from
Project Settings > Gameplay Tags (multiple databases merge into the registry at load).

Dependencies

• com.unity.collections 2.6.2, com.unity.mathematics 1.2.5, com.unity.nuget.newtonsoft-json
3.2.1 — real UPM packages, listed in package.json, resolved automatically.
• Heathen.GameFramework (Unity-Game-Framework repo) — not in package.json. It's a hard
  .asmdef reference (Heathen.GameplayTags.asmdef → Heathen.GameFramework), the same
  non-UPM dependency-guarding pattern used elsewhere in Heathen's Unity products: install
  Unity-Game-Framework alongside this package, don't expect it in the manifest. It supplies the
  Subsystem/ISubsystemDebug base for GameplayTagsSubsystem.
• Unity's own xxHash3 (Unity.Collections.xxHash3.Hash64, built into com.unity.collections) —
  no separate xxHash dependency needed on this engine (O3DE and Godot ports each vendor their own).

Common tasks

• Register/author tags: Project Settings > Gameplay Tags — create a GameplayTagsData
  asset, type a dot-path (e.g. Effects.Buff.Strength) into the New Tag field. Intermediate
  segments are implied automatically.
• Look up / compare tags in code: GameplayTag.FromName(...), implicit string/ulong
  conversions, IsAncestorOf.
• Give an entity a tag set: a GameplayTagCollection field — AddTag/RemoveTag/Contains.
  (Foundation is code-only here; the no-code GameplayTagCollectionComponent is Toolkit-tier.)
• Stack-count values on a tag (buff stacks, ammo count, etc.): collection.Apply(tag, GameplayTagArithmetic.Add, n), read back via GetValue(tag).
• Data-driven conditional logic: GameplayTagCondition list + EvaluateAll, or bundle a
  mutation with its own guard conditions via GameplayTagOperation.
• React to a tag's value changing: GameplayTagCollection.Subscribe(tag, callback, exactMatch)
  or the collection-wide Changed event.
• Use tags/hierarchy inside a Burst job: collection.GetSnapshot(Allocator.TempJob) and/or
  GameplayTagRegistry.GetNativeIntervalMap(Allocator.TempJob); dispose both when the job
  completes.
• See what tags exist and where they come from: Project Settings > Gameplay Tags panel
  (tree view, inline rename, filter); tools implement ITagSource to report provenance there.

Where full usage docs live

KB: https://heathen.group/kb/gameplaytags-welcome/ (confirmed live in source, via
GameplayTagsSubsystemHealth.DocumentationUrl). No per-component KB article slugs were found
committed in this repo to cite beyond the welcome page — check the live KB for anything more
specific before assuming a URL.

Version

com.heathen.gameplaytagsfoundation/package.json (version field, currently 1.0.10) +
com.heathen.gameplaytagsfoundation/CHANGELOG.md (currently a single baseline entry, prior
history not itemized).