Multi Tag

One tag per GameObject was never enough.
An enemy that is also interactable. A pickup that is also a quest item. An NPC in two factions. Unity's built-in tag system gives you exactly one tag from one fixed list, so you end up faking it with layers, booleans, enums, and GetComponent chains scattered across your project.

Multi Tag fixes the actual problem. 
Attach one component, type as many tags as you want, and query them from code or PlayMaker with one line.

Find anything in one query

csharp
gameObject.AddTag("Character.Enemy.Boss");
gameObject.HasTag("Character.Enemy"); // true, hierarchical
List enemies = MultiTagRegistry.FindAllWithTag("Character.Enemy");
No FindObjectsOfType. No GetComponent loops. A global registry answers exact queries in O(1) and keeps itself up to date as objects spawn and die. It also resets correctly under Unity 6's Fast Enter Play Mode, so your queries stay clean between play sessions.

Gameplay Tags, the Unreal way
Tags use dot-notation hierarchy, inspired by Unreal's Gameplay Tag system:
Character.Enemy.Boss
Interactable.Door
Pickup.Weapon.Sword
Query "Character" and you get every enemy, boss, and ally under it. Narrow to "Character.Enemy" and allies drop out. Zero comparison logic written by you. If you came from Unreal and miss Gameplay Tags, this is that workflow in Unity.

See every tag your scene actually uses
The Tag Manager (Tools > MultiTag > Tag Manager) holds your preset library and now shows live usage counts for every tag in your open scenes: how many objects carry each tag, exact and including child tags, with one click to select them all in the Hierarchy. Spot dead presets, find every "Interactable" in the scene, and pull unsaved in-scene tags into your presets without hunting.

A tag UI you can hand to designers
Tags render as clean chips in the Inspector with one-click removal, live autocomplete from your presets, and full multi-object editing: select fifty objects, see which tags are shared and which are partial, add or remove across the whole selection with Undo.

No-code with PlayMaker (optional)
Eight ready-made PlayMaker actions: Add Tag, Remove Tag, Has Tag, Get Tags, Find First With Tag, Find All With Tag, Any With Tag, Count With Tag. PlayMaker is not required and not included. The actions compile only when PlayMaker is present.

[TagReference] dropdown for your own scripts
Put [TagReference] on any string field and it becomes a tag picker dropdown in the Inspector, with the dot-hierarchy as nested submenus. No custom editor code.
csharp
[TagReference]
public string targetTag = "Character.Enemy";
Works with Hierarchy Pro

Multi Tag is the tag layer of an organized Unity project. Pair it with Hierarchy Pro (rule-based hierarchy styling from BlizStudio) and your tagged objects can color, icon, and badge themselves in the Hierarchy automatically. Tag it once, see it everywhere.
What's included
MultiTag component: attach, add tags, done
MultiTagRegistry: fast global queries, exact and hierarchical
Tag Manager window with presets, live usage counts, and select-by-tag
Custom Inspector with chip UI, autocomplete, and multi-object editing
MultiTagExtensions: fluent API on GameObject and Component
[TagReference] attribute + PropertyDrawer
8 optional PlayMaker actions (PlayMaker not required)
Three importable samples and full PDF documentation

Requirements
Unity 2022.3 LTS or later. Works with Fast Enter Play Mode.
No third-party dependencies. Editor windows and runtime code, nothing renders in your build scenes.