> ## Documentation Index
> Fetch the complete documentation index at: https://docs.npcbuilder.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Unreal Engine Plugin

> Blueprint-based AI NPC integration for Unreal Engine

<Info>
  The NPC Builder Unreal plugin adds asynchronous Blueprint nodes so you can chat with AI‑powered NPCs without leaving the editor.\
  It supports Unreal Engine 5.0 and higher.
</Info>

## Prerequisites

* Unreal Engine 5.0+
* NPC Builder account with an **active plan**
* Client ID / Secret (or Bearer token) generated in **Developers → API Keys**

## 1 · Install the plugin

<Steps>
  <Step title="Download">
    Get <code>NPCBuilder.unrealplugin</code> from the Unreal Marketplace (or company download link).
  </Step>

  <Step title="Enable in project">
    Copy the plugin into your project’s <code>Plugins/</code> folder  →  restart the editor.\
    Then open **Edit → Plugins** and ensure <em>NPC Builder SDK</em> is ticked.
  </Step>
</Steps>

## 2 · Configure credentials

Add credentials to <code>Config/DefaultGame.ini</code>:

```ini theme={null}
[/Script/NPCBuilderSDK.NPCBuilderSDKSettings]
ClientId=YOUR_CLIENT_ID
ClientSecret=YOUR_CLIENT_SECRET
GameId=YOUR_GAME_ID
BearerToken=YOUR_BEARER_TOKEN ; optional
```

<Callout type="warning">
  If both <code>ClientSecret</code> and <code>BearerToken</code> are present, the plugin prioritises <code>ClientSecret</code>.
</Callout>

## 3 · Blueprint workflow

<Steps>
  <Step title="Create Session">
    Use the <strong>Create Session</strong> node to obtain <code>Session ID</code>.\
    Provide <code>ClientId</code>/<code>ClientSecret</code> pins only if not set in <code>DefaultGame.ini</code>.
  </Step>

  <Step title="Update Character">
    Pass the <code>Character ID</code> (from the dashboard) and change optional fields (model, tone, events).
  </Step>

  <Step title="NPC Interaction">
    Send player text; the node returns <code>response</code> plus <code>character\_events</code>.\
    Use the response pin to update UI and parse events for gameplay.
  </Step>

  <Step title="Reset Conversation (optional)">
    Clear memory when the player leaves or you need a fresh start.
  </Step>
</Steps>

## 4 · Handling events

Events defined on the platform appear in <code>character\_events</code> or <code>user\_events</code> arrays.

```blueprint theme={null}
Event OnNPCEvent
 ├── Branch  (EventName == "dance")
 └── Play Montage (NPCA_DanceMontage)
```

Each event can include a referenced item. Use the plugin’s delegate to fetch the mapped <code>GameObject</code>:

```c++ theme={null}
npcInteractions->OnGetItemObject.AddDynamic(this, &AMyActor::HandleItem);
```

<Tip>
  All plugin Blueprint nodes are **asynchronous**—network calls never block the game thread.
</Tip>

<Note>
  Need a REST example instead of Blueprints? See <a href="/interactions-api-guide">Interactions API guide</a>.
</Note>