Unreal Engine
Description
Unreal Engine is a professional-grade real-time 3D creation platform created by Epic Games and used to build games, films, architecture visualizations, virtual production sets, training simulations, and interactive experiences. First demonstrated publicly in the 1998 first-person shooter game Unreal, the engine has been under continuous development for more than two decades and today powers some of the most visually ambitious games and productions across the industry.
The engine runs on Windows, macOS and Linux as a development environment, and it compiles and deploys projects to a wide range of target platforms including PC, Mac, consoles (PlayStation 4, PlayStation 5, Xbox One, Xbox Series X and S, Nintendo Switch), mobile devices (iOS and Android), and VR and AR headsets. The source code is available on GitHub to all licensed users.
The current major generation, Unreal Engine 5, was released in April 2022. It introduced Nanite and Lumen — two foundational rendering technologies that changed the way games handle geometry and lighting — and has since received major incremental updates adding systems for open world streaming, procedural content generation, physics simulation, character creation, animation, and more.
HISTORY
Epic Games founder Tim Sweeney started work on the first Unreal Engine in 1995, working on it mainly for the Unreal game. That first engine supported Windows, Linux, Mac and Unix and used either software or early hardware rendering. After the release of Unreal in 1998, Epic started licensing the engine to other studios.
Unreal Engine 2 added support for hardware rendering and introduced console support, running on PlayStation 2, Xbox and GameCube. Unreal Engine 3 (2006) introduced multithreading and DirectX as its graphics baseline, followed by iOS and Android support.
Unreal Engine 4 (2014) introduced physically based materials, the Blueprints visual scripting system and vastly improved tools for modern hardware. Initially sold as a $19/month subscription with royalties, Epic switched it to a free-to-download model in March 2015 with a 5% royalty on commercial products over $1 million in revenue. UE4 launched the Unreal Marketplace in September 2014, which enabled third parties to sell and share assets and plugins.
Epic unveiled Unreal Engine 5 in May 2020 with a live demo on PlayStation 5. Early access was released in May 2021, and the official release was in April 2022. Notable UE5 games include Black Myth: Wukong, Clair Obscur: Expedition 33, Avowed, Senua’s Saga: Hellblade II, Remnant 2, and Fortnite (which migrated to UE5 in December 2021).
NANITE: Virtualized Geometry
Nanite is Unreal Engine 5’s virtualized micropolygon geometry system and one of its most important technical advances. Traditional game development meant that artists had to create multiple versions of each 3D model at different levels of detail, manually managing polygon budgets to maintain stable frame rates. Nanite takes care of most of this work.
With Nanite enabled, artists can import film-quality 3D assets – photogrammetry scans, ZBrush sculpts, or CAD data – with hundreds of millions or even billions of polygons and place them directly into a scene. The engine streams and renders only the detail the camera can actually see at any given moment, automatically adjusting without any visible pop-in or loss of quality. Polygon count limits, draw call budgets, and time-consuming normal map baking are no longer limitations when working with Nanite geometry.
Unreal Engine 5.7 introduced Nanite Foliage as an experimental feature, which extends Nanite’s efficiency to dense vegetation. It uses Nanite Voxels to render huge numbers of overlapping elements like tree canopies and ground cover at stable frame rates, and supports skeletal animation for wind and movement of foliage entirely on the GPU.
LUMEN: DYNAMIC Global ILLUMINation
Lumen is Unreal Engine 5’s real-time global illumination and reflections system. Traditional engines required artists to bake lighting information into static textures — a process that could take hours and made dynamic lighting changes impossible. Lumen removes the need for pre-baked lighting and makes light in a scene completely dynamic.
With Lumen active, light bounces realistically off surfaces, fills in shadows with indirect lighting, and reflects accurately from materials. Artists can alter the sun angle for a time of day cycle, blow a hole in a ceiling, or turn on a flashlight, and the entire scene’s indirect lighting and reflections update accordingly in real-time.
Lumen has two modes of operation: Software Ray Tracing: Mesh Distance Fields, which can be used on a wide range of devices with a coverage range of up to 800 meters from the camera. Hardware Ray Tracing utilizes the ray tracing hardware on supported GPUs for higher fidelity results. Both modes are available in one project and Lumen automatically chooses the right method depending on hardware.
Unreal Engine 5.5 introduced MegaLights, a companion system that enables thousands of dynamic shadow-casting lights to efficiently render in the same scene. In testing, Epic showed more than 1,700 ray-traced lights active at once. As of UE5.7, MegaLights moved into Beta with the addition of support for directional lights, soft shadows, shadow casting particles in the Niagara VFX system, and improved hair shading.
BLUEPRINTS Visual Scripting
Blueprints is Unreal Engine’s node-based visual scripting system, introduced in Unreal Engine 4 as a successor to the previous Kismet system. It enables developers to build game logic, character behavior, UI interactions, and gameplay systems by linking nodes in a graph instead of writing code. Each node represents a function, event, or variable, and connections between nodes define the flow of logic.
Blueprints are used all throughout the industry by both beginners and experienced teams. Designers who don’t write C++ use Blueprints to create full gameplay systems, user interfaces and environment behaviors. Programmers use them to expose functionality from C++ code for the artists and designers to customize without touching source files.
Blueprints compile into native code at runtime, so performance is reasonable for most use cases. Very performance-critical systems, such as complex AI processing or physics calculations run on many thousands of entities, are usually written directly in C++. Blueprints and C++ are completely interoperable, and most professional projects use both.
WORLD Partition and Open-World Streaming
World Partition is Unreal Engine 5’s large world management system. In previous versions of the engine, building a massive open world involved manually dividing the level into dozens of sublevels, carefully managing what was loaded when, and dealing with data conflicts when multiple team members were working on different pieces. World Partition automates this completely.
With World Partition, there is a single persistent level that is a world. The engine automatically splits it with a grid and streams cells in and out depending on where the player is. The system takes care of data loading, memory management, and level of detail transitions without intervention from the developer and multiple team members can work on different parts of the same world at the same time without conflicts.
This system enables large, detailed open worlds to be achieved for teams of all sizes. As of 2025, World Partition is employed in full production in a wide variety of games and is regarded as a standard workflow for open world development in Unreal Engine 5.
CHAOS PHYSICS
Chaos is Unreal Engine 5’s physics simulation system, which replaces the previous PhysX backend. It handles a wide range of physical simulations including rigid body dynamics, destruction, cloth, hair, fluid and ragdoll physics.
Chaos Destruction is a way to make objects in a game world fracture and break apart in real time based on forces applied to them, creating visually convincing destruction without pre-authored break animations. Chaos Cloth is used to simulate the behavior of fabric on characters and objects. Chaos Hair deals with the strand-based hair and fur, which MetaHuman characters use by default.
Each subsystem (Chaos Cloth, Chaos Destruction, Chaos Fluids, Chaos Hair) gets individual updates in each engine release. UE5.7 introduced one-way physics collisions for more natural ragdoll behavior.
ANIMATION TOOLS
Unreal Engine 5 comes with an in-editor animation suite that helps to minimize the need to round-trip between Unreal and external digital content creation (DCC) tools such as Maya or 3ds Max.
Control Rig is the in-editor rigging system for creating rigs for characters. Animators can use it to pose and keyframe characters directly within the Unreal Editor using Sequencer, Unreal Editor’s cinematic and animation timeline tool. Control Rig Physics, introduced in UE5.6, introduces procedural movement such as swaying clothes or jiggling accessories directly in the rig.
The IK Retargeter is used to retarget existing animations from one skeleton to another. This makes it practical to reuse animation libraries for different character proportions. Unreal Engine 5 also supports Machine Learning Deformers, which use pre-trained machine learning models to generate high-quality real-time mesh deformations on character bodies that would otherwise require expensive simulation.
UE5.7 refactored the core animation editing experience with a refactored Animation Mode, Selection Sets for quick access to rig control groups, an improved IK Retargeter, and improved tools for sculpting and weighting meshes in the Skeletal Editor.
SEQUENCER
Sequencer is Unreal Engine’s cinematic editing and animation timeline tool, used for creating cutscenes, gameplay cinematics, and virtual production content. It works similarly to a non-linear video editor but in real-time in the engine. Sequencer is responsible for camera placement and movement, character animation, lighting changes, audio, particle effects and scene events along a timeline.
Virtual production studios and film productions utilize Sequencer with in-camera VFX workflows, where Unreal Engine is used to render a background on a large LED wall in real-time as actors perform in front of it. Movie Render Queue and Movie Render Graph (added and expanded in UE5.x releases) offer offline high-quality rendering export for final visual effects and animation production.
PROCEDURAL Content Generation
The Procedural Content Generation (PCG) framework introduced in Unreal Engine 5.2 lets developers generate large amounts of content automatically using node-based rules instead of placing assets by hand. Artists specify rules for the distribution of objects, materials or structures on surfaces, and the engine generates the result. PCG is production ready as of UE5.7.
The Procedural Vegetation Editor (PVE), introduced in UE5.7 as an experimental feature, is a build on PCG that allows artists to create and customize high-quality vegetation within the engine. It produces Nanite compatible assets and integrates with Quixel Megaplants — a library of scan-based vegetation recipes available through Fab.
FAB AND ASSET MARKETPLACE
Fab is Epic’s unified content marketplace, replacing the previously used Unreal Marketplace and Quixel Bridge as the primary destination to find and purchase assets, plugins, tools, and templates for Unreal Engine projects. Developers can browse through thousands of 3D models, materials, sound effects, animation packs, code plugins, and full project templates.
Epic acquired photogrammetry company Quixel in 2019, making the Megascans library – tens of thousands of photorealistic real-world scan assets including surfaces, objects and vegetation – freely available to all Unreal Engine licensees. These assets, now distributed through Fab, can be imported directly into projects at different resolution levels.
The Fab marketplace tab is available within the Unreal Editor and the Epic Games Launcher and web.
VIRTUAL REALITY AND AUGmented Reality
Unreal Engine supports development for VR and AR headsets including headsets from Meta (Oculus), Valve (SteamVR), Sony (PlayStation VR and PSVR2), and others. The engine offers templates and sample projects that are intended for VR, and its rendering pipeline supports the stereo rendering requirements of headset displays. OpenXR is supported as the cross-platform XR API, which supports cross-device compatibility without the need for separate platform-specific implementations.
INDUSTRIES BEYOND GAMES
Unreal Engine is used extensively outside the game development field. Film and television productions use it for virtual production on LED volumes and for previs. Architectural firms use it for interactive real-time walkthroughs of buildings and interiors. Automotive companies use it for product configurators and design visualization. Training and simulation companies use it for industrial, military and medical training applications. Live broadcast productions use its real-time rendering for graphics and virtual sets.
LICENSING
Unreal Engine is available for free with full access to all features and C++ source code.
For game developers and developers that build applications that use Unreal Engine code at runtime and distribute to end users: The engine is free to use. A 5% royalty is applied to worldwide gross revenue over the first $1 million USD in the lifetime of a product. Revenue earned from sales on the Epic Games Store is not subject to royalty calculations. Under the “Launch Everywhere with Epic” program, which goes into effect January 1, 2025, the royalty rate drops to 3.5% for Windows, macOS, and Android games published on the Epic Games Store at the same time as other platforms.
For students, educators, and hobbyists: Free with no royalty obligations.
For non-game commercial users (VFX studios, architecture firms, broadcast companies, automotive visualization, and so on) who generate more than $1 million USD per year and are not distributing engine-based runtime applications to third parties: A seat-based subscription of $1,850 per seat per year applies, introduced with Unreal Engine 5.4 in April 2024. This subscription comes with access to Twinmotion and RealityCapture. This pricing is applicable to UE5.4 and later; users continuing to use UE5.3 or earlier are not affected.
