Why Big Studios Are Giving Up Their Own Engines for Unreal
CD Projekt shelved REDengine, Halo left Slipspace, and custom engines now power just 13% of new Steam games. Yet Rockstar, Capcom and EA are sticking with their own tech. Inside the biggest shift in how blockbusters are built.
For most of gaming history, owning your engine was a badge of honour. id Software had id Tech, Bungie had its Halo engine, CD Projekt built REDengine for The Witcher and Cyberpunk 2077. Your technology was your identity, and part of your competitive edge.
That is changing fast. According to Video Game Insights, games built on custom engines made up 71% of Steam releases in 2012 but only 13% in 2024, and in 2024 their share of Steam revenue fell below half for the first time since 2014. Two of the biggest names in blockbusters have joined the shift: CD Projekt is making its next Witcher in Unreal Engine 5, and Microsoft's Halo Studios released Halo: Campaign Evolved, built in Unreal, on July 28, 2026.
The CD Projekt decision
CD Projekt's move was the one that surprised people most. REDengine powered The Witcher 3 and Cyberpunk 2077, two of the most technically ambitious games of their time. But Cyberpunk 2077's troubled 2020 launch, especially on older consoles, showed how hard it is to build a huge game and its engine at the same time.
In 2022, CD Projekt announced a strategic partnership with Epic and said its next Witcher would be made in Unreal Engine 5. Instead of simply licensing the engine, its engineers work with Epic on features for large open worlds, which go back into Unreal for everyone. In June 2025, the two companies showed a Witcher 4 technical demo running at 60 frames per second with ray tracing on a base PS5.
Halo leaves Slipspace
Halo's move was just as symbolic. In October 2024, 343 Industries renamed itself Halo Studios and announced it would make future Halo games in Unreal Engine 5, leaving behind the Slipspace engine used for Halo Infinite. The first result, Halo: Campaign Evolved, is a remake of the original Halo campaign and launched on PS5 as well as Xbox and PC, priced at $49.99 on Steam.
The reasons are practical. With Unreal, studios can hire developers who already know the tools, share work with outsourcing partners easily and spend less on maintaining their own technology. Epic, meanwhile, spends heavily on features such as Nanite for detailed geometry and Lumen for lighting, which few single studios could match.
Who is sticking with their own engines
Not everyone is moving. Some of the biggest publishers still see their engines as a key advantage:
- Rockstar Games uses its RAGE engine for Grand Theft Auto VI, due on November 19, 2026.
- Capcom's RE Engine powers Resident Evil, Monster Hunter Wilds and Street Fighter 6.
- EA built Battlefield 6 on its Frostbite engine.
- Sony's Guerrilla Games developed Decima, which Kojima Productions also used for Death Stranding.
These companies have something in common: a steady stream of huge games that can justify the cost of large internal engine teams. For them, owning the technology means they can tune it exactly for their games and avoid paying royalties on billions in sales.
The risks of one engine for everyone
The shift has downsides. When many big games use the same engine, they share the same problems. Unreal Engine 5 games have been criticised for shader compilation stutter, the brief freezes when a game prepares graphics effects on PC, and for heavy hardware demands. Epic has been working on fixes, and CD Projekt's partnership is partly about solving them.
There is also a question of variety. Distinctive engines have often produced distinctive games. A world where most blockbusters share one toolset may be more efficient, but it could also feel more uniform.
Why it matters
The move to Unreal is a sign of how expensive and complex big games have become. Building a game is hard enough; building the engine at the same time is a luxury fewer companies can afford.
WGC's take: for players, the switch is mostly good news, because it should mean fewer broken launches and better performance as Epic and big studios fix shared problems together. The risk is a loss of personality. The best outcome is the one we have now: Unreal as a strong default, with Rockstar, Capcom and others proving that a great in-house engine is still worth it. For more on the money side, see our long read on the 2026 engine wars.