Inside The Witcher 4 Unreal Engine 5 Tech Demo: CD Projekt RED + Epic Deep Dive Interview

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Published on June 14, 2025 2:14:45 PM ● Video Link: https://www.youtube.com/watch?v=OplYN2MMI4Q

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Unreal Fest 2025 kicked off in spectacular style with a stunning demonstration of The Witcher 4 content running in a new Unreal Engine 5 demo, showcasing key advancements made for the technology - and all running on a standard PlayStation 5 with hardware RT at 60fps. Alex visited CD Projekt RED's studio in Warsaw for a deep dive interview with CDPR and Epic, discussing the creation of the demo with some of the key people who made it.

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00:00:00 Introduction
00:01:36 When did the cooperation begin for the TW4 Tech Demo?
00:02:47 Why did CDPR switch to Unreal Engine?
00:04:11 Why target and show the demo on PlayStation 5 at 60 fps?
00:06:20 60 FPS: a challenge or a limitation?
00:07:33 How was Hardware Lumen brought up to 60 fps on console?
00:08:36 Why use hardware ray tracing when the software path already exists and ran better?
00:10:52 What affect does RTGI and Reflections have on Art Design?
00:11:57 How does Lumen affect cinematic design?
00:13:36 How was the world and terrain created for this demo?
00:15:31 How did the team view the paradigm shift in how vegetation is made?
00:19:50 Can the new vegetation technology be used elsewhere?
00:21:20 How is the new voxel technology lit and shaded?
00:22:56 How was Virtual Shadow Maps brought up to 60 fps for this demo?
00:24:44 How was the demo's "flawless" frame-time achieved?
00:27:40 Can UE5 have flawless cutscenes on all platforms?
00:30:32 Where do frame-time issues usually occur in UE5 projects?
00:32:38 Will UE5 ever be rid of the "render thread" or "game thread"?
00:33:53 How was RedEngine designed and what is its affect on how CDPR uses UE5?
00:36:45 How would CDPR potentially scale the graphics beyond PS5?
00:38:49 How would CDPR potentially scale the graphics below PS5?
00:39:27 How did RedEngine manage PSOs?
00:41:24 What is a moment or aspect of the project which you are particularly proud of?
00:47:50 Conclusion