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Engine switch
CD Projekt Red announced in March 2022 that The Witcher IV would use Unreal Engine 5, developed by Epic Games. This replaced the proprietary REDengine that powered The Witcher 2, The Witcher 3, and Cyberpunk 2077.
CDPR had used REDengine for over a decade. Moving to Unreal Engine 5 meant retraining the development team on new tools, but it also opened access to Epic's ongoing R&D, a larger hiring pool of developers already familiar with Unreal, and faster iteration. CDPR described it as a strategic partnership rather than a standard licensing arrangement.
The tech demo
The June 2025 tech demo at the State of Unreal ran approximately 14 minutes. It was played live by cinematic director Kajetan Kapuscinski, with narration from game director Sebastian Kalemba and Epic Games' Wyeth Johnson.
CDPR explicitly stated: "A first look at the advanced technology powering The Witcher 4, but not The Witcher 4 itself." The demo was purpose-built to showcase UE5 capabilities, and the final game may look different.
Technical specifications
Component | Requirement |
|---|---|
Engine version | Unreal Engine 5.6 |
Hardware | Base PlayStation 5 (not PS5 Pro) |
Frame rate | 60 FPS with ray tracing (Lumen in hardware tracing mode) |
Internal resolution | Approximately 900p average, with dips to the mid-800s |
Upscaling | Temporal Super Resolution (TSR) to an estimated 1440p output |
Technologies demonstrated
Item | Description |
|---|---|
FastGeo Streaming | Co-developed by CDPR and Epic for fast environment loading without visible loading screens |
Nanite Foliage | Extremely high polygon vegetation (arriving in UE 5.7) that scales automatically by distance |
MetaHuman with Mass AI | Over 300 individually animated NPCs on screen in Valdrest, each behaving independently |
Motion Matching | Advanced animation for Kelpie's horse movement, blending gaits based on speed and terrain |
Chaos Flesh | Physics-based skin and muscle deformation using machine learning, visible in Kelpie's shoulders during galloping |
ML Deformer | Facial animation technology that shows fatigue and emotion on Ciri's face |
Ray tracing | Real-time Lumen lighting at 60 FPS |
Cinematic trailer rendering
The cinematic reveal trailer from December 2024 was rendered in a custom build of Unreal Engine 5 running on an NVIDIA GeForce RTX 5090 (which was unannounced at the time). The trailer was produced in collaboration with Platige Image, the studio behind all previous Witcher game cinematics. CDPR stated it was "powered by the same tech that The Witcher IV is built on, using assets and models from the game itself."
Collaboration with Epic Games
CDPR engineers have contributed tools and optimizations back to the engine, including FastGeo Streaming. Epic has provided dedicated technical support for CDPR's requirements. The relationship is described as a close development partnership, with both companies benefiting from shared R&D.