I found this post in the Steam discussions by a user named SiTWulf regarding the upcoming engine upgrade mentioned in [02.27.26] Weekly Update & Next Engine Preview .
If you’re interested in future features which we’ll be able to playtest on March 5, here’s a re-post: (Source: Weekly Update & Next Engine Preview :: inZOI Events & Announcements)
"Hey everyone,
I’ve been digging into the differences between UE 5.4 and the upcoming UE 5.6 features.
The main theme for 5.6 is clear: Optimization for 60 FPS on consoles and moving the entire creative pipeline directly into the Editor.
- Performance: The Push for 60 FPS
While 5.4 introduced major stability for Nanite and Lumen, 5.6 refines the Hardware Ray Tracing (HWRT) and Parallel Rendering.
Lumen Optimizations: Significant reduction in CPU overhead. It’s now much more viable to hit 60Hz targets on current-gen hardware without massive visual sacrifices.
Nanite Tessellation: Improved memory management over 5.4, especially regarding VRAM pressure on mid-range GPUs (like 6GB/8GB cards).
- The “In-Engine” Revolution (MetaHumans & Animation)
This is the biggest workflow change. We are moving away from external apps/bridges.
MetaHuman Creator In-Engine: In 5.6, you can sculpt, edit, and create MetaHumans directly inside the UE Editor. No more jumping back and forth to a web browser for every minor tweak.
Rig Physics: 5.6 introduces real-time physics for Control Rigs. You can now simulate secondary motion (hair, cloth, jiggle) while you are animating, rather than waiting for a post-process simulation.
- World Building & PCG (Procedural Content Generation)
Biome Core v2: Building massive open worlds is much faster. 5.6 enhances the PCG framework to allow for more complex, rule-based biome generation that is easier to debug than the initial 5.4 implementation.
Foliage Rendering: Massive improvements in how Nanite handles “masked” textures (leaves/grass), drastically reducing the “Overdraw” that used to kill performance in 5.4.
- Quality of Life & Ecosystem
Fab Integration: While 5.4 started the transition, 5.6 is fully built around the Fab Marketplace. It’s a unified experience for Megascans, Sketchfab, and Marketplace assets within a single UI.
Incremental Cooking: 5.6 significantly reduces iteration times by only cooking what has actually changed since your last build."
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I understand at least 75% #Need Science to English translator Plox 
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I’ll do my best to break it down for you 
- Better Performance & Smoother Gameplay
The big goal is making games run more smoothly, especially targeting stable 60 FPS on consoles and modern hardware.
- Improved Graphics Without Killing Performance
Lighting and detailed geometry are better optimized, meaning strong visuals with less strain on your system. Even mid-range PCs should benefit.
- Character Creation Happens Directly in the Editor
You’ll be able to create and edit MetaHumans directly inside the engine, without jumping to external apps or websites.
- More Realistic Animations in Real Time
Things like hair, clothing and secondary movements can now react naturally while being animated. No need to wait for separate simulations.
- Faster Open World Creation
Building large environments (like biomes and landscapes) becomes easier, more flexible and faster to work with.
- Better Foliage Performance
Grass, leaves and dense vegetation should perform much better compared to the current version.
- Improved Asset Marketplace Integration
All assets (Marketplace content) are now unified into one streamlined system.
- Faster Development Iteration
The engine now only rebuilds what actually changed, meaning quicker test builds and shorter waiting times for developers.
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That sounds to good to be true, that always makes me wary ^^’
So I asked Google AI if it’s a good coice to upgrade Ureal Engine in an existing game, that’s what he said:
Quote:
Upgrading an existing game to a newer version of Unreal Engine (e.g., from UE4 to UE5 or from 5.1 to 5.4) is a high-risk, high-reward decision
. While it offers access to cutting-edge features like Nanite, Lumen, and improved performance workflows, it can cause significant technical, financial, and time-related setbacks.
Whether it is a “good choice” depends heavily on the project’s stage and the necessity of the upgrade.
When Upgrading is a Good Choice
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Early Development: Upgrading is generally recommended in the prototyping or early, pre-production phases.
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Need for Specific Features: If the game requires new lighting (Lumen), geometry (Nanite), or performance improvements that are not available in the current engine version.
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Long-Term Support (Live Service): For games intended to run for years, updating ensures compatibility with new hardware, OS updates, and allows for better maintenance.
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Incremental Upgrades: Moving up small, iterative versions (e.g., 5.3 to 5.4) is generally easier and less risky than major leaps (e.g., 4.27 to 5.0).
When Upgrading is a Bad Choice
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Close to Launch: AAA studios generally stop major engine updates 6–12 months before release to ensure stability.
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Complex/Finished Projects: If the project is mature, stable, and already looks good, the time spent fixing broken shaders, plugins, and code often outweighs the benefits.
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“If it ain’t broke, don’t fix it”: If the current engine version supports all required features, upgrading just to be on the newest version can introduce unnecessary bugs.
Potential Risks and Challenges
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Broken Functionality: Upgrading often breaks plugins, code APIs, and assets, requiring significant man-hours to fix.
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Performance Degradation: Newer versions (especially UE5) can be more resource-intensive, potentially hurting performance on older hardware if not properly optimized.
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Increased Workload: Migration can be a massive undertaking, sometimes taking over a year for complex games, as seen with Satisfactory.
Key Tips for Upgrading
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Use a Branch/Fork: Never upgrade the main project file directly. Always create a copy, migrate, and test thoroughly before merging.
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Read Release Notes: Understand what is changing.
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Consider “Skip” Strategy: Historically, many developers skipped every other major engine version (e.g., sticking with 4.26) to maintain stability.
Summary: For a newly launched game looking to stay “future-proof” upgrades are necessary. For a team near completion, it is usually better to “lock in” the engine version and finish the game.
/Quote End
As much as I’d love some graphic/lighting improvements, Imo it is a high risk decision to put an Unreal Engine upgrade on top of the wonky jenga tower inZOI currently is.
And we already had better graphics/lighting.
2 Likes
I’m really hopeful that the engine upgrade will bring long-term benefits, especially for older setups and the GPU and VRAM issues we’ve encountered since launch. We should always also keep possible negative effects in mind, so the insights you provided are very cool. Thank you
I just googled which rather modern games had engine upgrades, just for reference: Echoes of Elysium (upgrade shortly before EA launch - yesterday), Nightingale (UE4 to UE5 pre-EA), Satisfactory (upgraded UE4 various times + changed to UE5 during EA), Escape From Tarkov (did various engine upgrades during production). I haven’t played all of them but know that each of them has a rather stable community, just like inZOI.
Of course we can only hope for the best and try to find as many bugs and glitches as possible from March 5 until the upgrade gets integrated for good. I like the approach from the team though. Betas, especially in grand games like life-sims, can be a real game changer IMHO. Can’t wait to put it to the test soon 
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Note that the list of new things possible in UE5.6 is from UE perspective, pulled from Epic’s change notes. Even after the upgrade to UE5.6, it does not mean that all these features will automatically be seen in the game.
Inzoi developers still have to make appropriate changes in the game (at code level) to implement whichever of these new features of UE5.6 are considered necessary and those that can be done without severely impacting the game at this stage.
In short, not all of the above stated new features may be implemented or seen in the game at this time. So better to word the beta feedback clearly, ask questions if a feature from UE5.6 was implemented if at all, and then post feedback/bugs.
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Yes, thank you for mentioning this. The upgrade supports the improvement mentioned above, but what gets implemented to which extend is up to the developers at all times 
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Let’s keep in mind that what the company cares about is SELLING. So, upgrading a game that’s a mess optimization-wise and sometimes struggles to run on high-end PCs to a engine that lets it run smoothly on mid-range PCs and consoles is a smart move (even if it means rewriting code). Unreal engine isn’t just a graphical upgrade for Inzoi, it also brings better distance culling (which everyone was asking for), more realistic animations, better physics and clothing collisions (so clothes won’t clip with zois anymore), smoother animation transitions, better crowds (the world could be more populated without sacrificing performance), and better facial expressions. There’s even a mode that generates facial expressions from audio with integrated emotions, so bad lip sync wouldn’t be an issue anymore. Bugs can always be fixed, but poor performance on a demanding game on an outdated engine can’t.
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