Unreal Engine

• 1. Introduction

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  Unreal Engine began as a single game's backbone. In 1998, Epic Games released Unreal, a first-person shooter built on technology that Tim Sweeney had been developing since 1995. Nobody could have predicted that this engine would eventually be used to film television series, train FBI investigators, and power the infotainment screens inside electric cars.

  The questions that follow are worth sitting with. How does a piece of software designed for shooting games on a PC end up as the virtual scenery behind actors on a Hollywood sound stage? How does a scripting language survive three generations of an engine before being voted out of existence in a massive internal meeting? And what does it mean that Unreal Engine now holds a larger share of the game market by units sold than any other engine on earth?

• 2. Seven Generations Deep

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  Tim Sweeney, the founder of Epic Games, started building Unreal Engine in 1995, three years before the game it was named for ever shipped. The earliest version ran on Windows, Linux, Mac, and Unix, and could toggle between software rendering and hardware rendering, supporting early 3D accelerators like the 3DFX Voodoo Graphics card via the 3DFX Glide API.

  Unreal Engine 2 made a decisive architectural shift. It dropped software rendering entirely and extended the engine's reach to consoles, adding support for the PlayStation 2, Xbox, and GameCube. Its first game appeared in 2002 and its last update shipped in 2005.

• 3. The Language Wars

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  UnrealScript, often abbreviated to UScript, was the scripting language that held Unreal Engine together through its first three generations. Tim Sweeney wrote it himself. He had already built an earlier game scripting language called ZZT-OOP, so UnrealScript was not his first attempt at solving the problem.

  Deus Ex lead programmer Chris Norden described UnrealScript as "super flexible" but flagged its low execution speed as a real limitation. The language was object-oriented, similar to Java, with all classes inheriting from a common Object class and no multiple inheritance. Unlike Java, it did not wrap primitive types in objects. Interfaces were only supported in Unreal Engine 3 and a small number of Unreal Engine 2 games.

  By the time Epic was planning Unreal Engine 4, the debate over UnrealScript's future became, by Sweeney's own account, genuinely unwieldy. He described a massive internal meeting where the team kept compiling larger and larger feature lists of what would need to be done to make the language competitive. At a certain point, Sweeney looked at the list and reached a conclusion. He later recounted the moment: "everything you're proposing to add to UnrealScript is already in C++. Why don't we just kill UnrealScript and move to pure C++? You know, maximum performance and maximum debuggability." At the 2012 Game Developers Conference, Epic made it official.

  The visual scripting gap that UnrealScript had partly filled was covered by Blueprints, which replaced an earlier system called Kismet.

  The successor language is called Verse, and it works differently from UnrealScript in almost every respect. Simon Peyton Jones, known for his work on the Haskell programming language, joined Epic in December 2021 as Engineering Fellow to help build it alongside his long-time colleague Lennart Augustsson. Sweeney conceived the language. It was presented publicly at Haskell eXchange in December 2022 as an open-source functional-logic language aimed at the Fortnite metaverse. A research paper titled The Verse Calculus: a Core Calculus for Functional Logic Programming was published alongside it. Verse launched in March 2023 as part of the Unreal Editor for Fortnite at the Game Developers Conference.

• 4. Hollywood on an LED Wall

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  The Mandalorian brought Unreal Engine to a mainstream audience in a way that no game release had managed. Jon Favreau and Lucasfilm's Industrial Light and Magic division worked with Epic to develop a technology called StageCraft, built on an approach Favreau had already used in The Lion King. The idea was to replace traditional chromakey green-screen backdrops with large LED screens displaying virtual environments rendered in real time by Unreal Engine. The result was recognized to look more natural than conventional visual effects compositing.

  Favreau then shared the StageCraft approach with Westworld producers Jonathan Nolan and Lisa Joy. The show had already explored virtual sets before the collaboration and had some technology in place; it integrated Unreal Engine through StageCraft for its third season.

  Other productions followed. The live-action series Fallout used the technology, as did the animated series Zafari, Barney's World, and Miraculous: Tales of Ladybug and Cat Noir beginning from its sixth season. Super Giant Robot Brothers is on the same list. Unreal Engine was also used for motion capture work on Lyle, Lyle, Crocodile.

  In January 2021, Deadline Hollywood reported that Epic was using its Epic MegaGrants to back an animated feature film called Gilgamesh, to be produced entirely in Unreal Engine by animation studios Hook Up, DuermeVela, and FilmSharks. That was the first time MegaGrants had backed an animated feature film. Epic also funded 45 additional film projects through MegaGrants, covering both feature-length and short productions. By October 2022, Epic was working with groups running over 300 virtual sets across the world.

  Orca Studios, based in Spain, worked with Epic during the COVID-19 pandemic to build multiple virtual filming stages using the same StageCraft model, at a time when restrictions on travel made location shooting difficult.

• 5. Beyond the Game World

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  Rivian is among the car manufacturers that have chosen Unreal Engine to power their infotainment systems. The engine's portability across platforms made it an option outside entertainment that its original designers probably never anticipated.

  In March 2012, Epic announced a partnership with Virtual Heroes of Applied Research Associates to create the Unreal Government Network, a program that managed Unreal Engine licenses for government agencies. Several projects emerged from that agreement. U.S. Army physicians received anaesthesiology training software. The FBI Academy developed a multiplayer crime scene simulation. The Intelligence Advanced Research Projects Activity used the engine to build applications designed to help intelligence analysts recognize and reduce cognitive biases in their work. The DHS Science and Technology Directorate and the U.S. Army's Training and Doctrine Command and Research Laboratory used it to build a first-responder training platform called Enhanced Dynamic Geo-Social Environment, or EDGE.

  Researchers have used Unreal Engine as the basis for virtual reality tools to explore pharmaceutical drug molecules. Architects and automotive designers have used it as a virtual environment to design buildings and cars before they are built. Cable news networks have used it to power real-time graphics.

  The commercial metrics are striking. Unreal Engine's market share among game engines rose from an estimated 17% in 2012 to 28% in 2024, against Unity's 50% share. By revenue from units sold, Unreal accounts for 31% against Unity's 26%, with proprietary engines taking a combined 42%. That puts Unreal ahead of Unity by the unit-sales measure. Guinness World Records recognized it as the most successful video game engine in 2014.

• 6. Awards and Legal Battles

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  The National Academy of Television Arts and Sciences gave Unreal Engine a Technology and Engineering Emmy Award in 2018 for three-dimensional engine software used in animation production. The Television Academy followed with a Primetime Engineering Emmy Award in 2020 for exceptional developments in broadcast technology. ASIFA-Hollywood added an Annie Award in 2021 for technical advancement in animation.

  Game Developer Magazine named it Best Game Engine in its Front Line Awards for 2004, 2005, 2006, 2007, 2009, 2010, 2011, and 2012. The Develop Industry Excellence Award for Best Engine went to the engine in 2009, 2010, 2011, 2013, 2016, 2017, and 2018.

  In 2020, Epic filed a legal action against Apple claiming anticompetitive behavior in Apple's iOS App Store. The dispute began when Epic uploaded a version of Fortnite that violated Apple's App Store terms. Apple removed the app and later threatened to terminate Epic's developer accounts entirely. That threat extended beyond Fortnite: it would have prevented Epic from updating Unreal Engine for iOS and macOS. A court agreed to grant Epic a permanent injunction against Apple on that specific point, finding that terminating the developer accounts would harm the many third-party developers who rely on Unreal Engine and had no part in the original dispute.

  The royalty model that governs commercial use charges 5% of revenues over one million US dollars, waived entirely for games published exclusively on the Epic Games Store. Epic had retroactively reduced its share of Unreal Engine Marketplace sales from 30% to 12% by July 2018, a change driven by the financial success of Fortnite Battle Royale.