Unreal Engine Developer Guide

Your agent for Unreal Engine game development — covering Blueprint visual scripting, C++ gameplay programming, material systems, and UE-specific architecture patterns.

When to Use This Agent

Choose Unreal Engine Developer Guide when:

• Developing games or applications in Unreal Engine 5
• Writing C++ gameplay code with UE5 frameworks
• Creating Blueprint visual scripts for rapid prototyping
• Building materials, particle systems, and visual effects
• Implementing Unreal-specific systems (Gameplay Ability System, Enhanced Input)

Consider alternatives when:

• You need Unity development — use a Unity agent
• You need Godot development — use a Godot agent
• You need web-based 3D — use a 3D Navigator agent

Quick Start

Copy
# .claude/agents/unreal-developer.yml
name: Unreal Engine Developer Guide
model: claude-sonnet
tools:
  - Read
  - Write
  - Edit
  - Bash
  - Glob
  - Grep
description: Unreal Engine 5 development agent for C++ gameplay, Blueprints, materials, and UE architecture patterns

Example invocation:

claude "Implement a Gameplay Ability System setup for a multiplayer action RPG — character attributes, basic attack ability, cooldown management, and replicated ability activation"

Core Concepts

Unreal Engine Architecture

System	Purpose	Key Classes
Gameplay Framework	Player, controller, game mode	ACharacter, APlayerController, AGameModeBase
Gameplay Ability System	Abilities, effects, attributes	UGameplayAbility, UGameplayEffect, UAttributeSet
Enhanced Input	Modern input handling	UInputAction, UInputMappingContext
Subsystems	Module-level services	UGameInstanceSubsystem, UWorldSubsystem
Data Assets	Runtime data containers	UDataAsset, UPrimaryDataAsset

UE5 Project Structure

Source/MyGame/
├── MyGame.Build.cs                # Build configuration
├── Core/
│   ├── MyGameGameMode.h/cpp       # Game rules and spawning
│   ├── MyGamePlayerController.h/cpp
│   └── MyGameCharacter.h/cpp
├── Abilities/
│   ├── MyAbilitySystemComponent.h/cpp
│   ├── MyGameplayAbility.h/cpp
│   └── MyAttributeSet.h/cpp
├── UI/
│   ├── MyHUD.h/cpp
│   └── Widgets/
└── Subsystems/
    └── MyGameSubsystem.h/cpp

Configuration

Parameter	Description	Default
ue_version	Unreal Engine version	5.4
language	Primary language (cpp, blueprint, both)	both
networking	Multiplayer support (none, listen, dedicated)	none
render_mode	Rendering (lumen, nanite, mobile)	lumen
input_system	Input approach (enhanced, legacy)	enhanced

Best Practices

1. Use UPROPERTY and UFUNCTION macros consistently. All exposed variables need UPROPERTY() with appropriate specifiers (EditAnywhere, BlueprintReadWrite, Replicated). All functions accessible from Blueprints need UFUNCTION(). Missing macros cause reflection system failures and silent bugs.

2. Implement gameplay systems in C++, expose to Blueprints. Write core systems (abilities, AI, networking) in C++ for performance and version control. Create Blueprint-friendly interfaces (BlueprintCallable, BlueprintImplementableEvent) for designers to extend without touching C++.

3. Use the Gameplay Ability System for ability-based games. GAS provides attribute management, ability activation, cooldowns, costs, and effects out of the box. Building a custom ability system is significantly more work for the same functionality.

4. Leverage Subsystems for global services. Instead of singletons, use UGameInstanceSubsystem for persistent services and UWorldSubsystem for level-scoped services. Subsystems are automatically created and destroyed by the engine.

5. Profile with Unreal Insights, not just the editor. Unreal Insights provides detailed CPU, GPU, memory, and network profiling. Build the Development configuration, run with -trace=default, and analyze the trace in Unreal Insights for accurate performance data.

Common Issues

Hot Reload causes crashes or stale data. Hot Reload in UE5 is unreliable for class structure changes. Use Live Coding for small code changes, and do a full editor restart for header changes, new UPROPERTY/UFUNCTION additions, or class hierarchy modifications.

Replicated variables don't sync in multiplayer. UPROPERTY(Replicated) requires GetLifetimeReplicatedProps() implementation with DOREPLIFETIME(). For custom replication conditions, use DOREPLIFETIME_CONDITION(). Check that the actor has bReplicates = true in the constructor.

Blueprint graph becomes unmaintainable spaghetti. Large Blueprints with hundreds of nodes are hard to debug and review. Break complex logic into Blueprint Functions, use Blueprint Interfaces for communication, collapse node clusters into named functions, and move performance-critical or complex logic to C++.