I asked Gemini (Google AI) "how long should it take a gaming studio to switch from cryengine to unreal engine?"
Converting a game from CryEngine to Unreal Engine is almost never a simple "conversion"—it is essentially a
re-creation of the game using existing art assets.
Because the two engines function fundamentally differently at the core, you cannot "copy-paste" the game. A realistic timeline estimate depends heavily on how far along the project is.
The "Rule of Thumb" Estimate
A common industry calculation for engine switching mid-project is:
Time Already Spent × 0.5 to 1.0 = Added Delay
- Example: If you have spent 18 months building a game in CryEngine, expect the switch to Unreal to delay your launch by 9 to 18 months.
Breakdown by Development Phase
| Project Phase | Estimated Delay | Feasibility |
| Pre-Production (Concept/Prototyping) | 2–4 Months | High. This is the best time to switch. You lose prototype logic but keep the design documents and art concepts. |
| Mid-Production (Vertical Slice Complete) | 6–12 Months | Medium Risk. You will keep your 3D models and textures, but you must rebuild all gameplay code, AI, and level design from scratch. |
| Late Production (Content Complete) | 1–2+ Years | Critical Risk. Generally considered "suicide" for a project. It is usually cheaper to hire CryEngine experts to fix your current bugs than to switch engines. |
Where the Time Goes (The "Conversion" Reality)
To understand why it takes so long, you have to look at what transfers and what doesn't.
1. The Easy Part: Art Assets (10-20% of the work)
- What Transfers: 3D Meshes (.fbx, .obj), Textures (.tga, .png), and Audio files.
- The Work: These can be bulk-imported into Unreal relatively quickly. However, you will still need to manually re-apply textures and configure collision meshes for thousands of objects.
2. The Hard Part: Code & Logic (60% of the work)
- What Transfers: Nothing.
- The Work:Even though both engines use C++, the "dialect" is completely different.
- CryEngine: Uses specific entity component systems and Lua/Flowgraph.1
- Unreal: Uses the AActor framework, heavily relies on Blueprints, and has its own C++ macros/garbage collection.
- Result: Programmers cannot copy code; they have to read the old code, understand what it did, and rewrite it entirely in Unreal syntax.
3. The "Invisible" Systems (20% of the work)
- Physics: CryEngine uses its own physics engine (or PhysX in newer versions); Unreal uses Chaos (in UE5) or PhysX (older UE4). Vehicles and ragdolls will feel completely different and require months of tuning to "feel" the same.
- AI: CryEngine’s AI system is distinct. Unreal uses Behavior Trees and the EQS (Environment Query System). All enemy behavior must be rebuilt from the ground up.
- Shaders: None of your materials transfer. Every water surface, glass window, and skin shader must be recreated using Unreal's Material Editor.
Estimates by Studio Size
- Indie Studio (5-10 people):
- Project: Single-player shooter.
- Conversion Time: 4–8 months.
- Advantage: Less legacy code to rewrite.
- Risk: The studio might run out of money during the transition.2
- AA Studio (30-80 people):
- Project: Multiplayer action game.
- Conversion Time: 12–18 months.
- Advantage: Can split teams (one team porting assets, one team rewriting code).
- Risk: "Feature creep." Teams often try to improve the game while switching, which bloats the timeline indefinitely.
- AAA Studio (200+ people):
- Project: Open World RPG.
- Conversion Time: 2+ Years.
- Reality: AAA studios rarely switch engines for a specific game mid-development. They usually finish the game on the old engine and switch for the sequel (e.g., CD Projekt Red moving from REDengine to Unreal 5 for the next Witcher).
Summary Recommendation
If your game is more than
40% complete, switching engines is likely a bad business decision unless:
- You have hit a technical wall that CryEngine absolutely cannot solve (e.g., console porting issues).
- You cannot find/hire enough CryEngine developers to finish the game.
Next Step: If you are currently evaluating this risk, would you like a checklist of
"Technical Dealbreakers" that would justify taking the hit to switch engines mid-project?