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# Satisfactory Under the Hood: Unreal, Significance Manager & Abstracted Belts
- URL: https://simstructures.com/satisfactory-under-the-hood/
- Published: 2026-08-31T18:31:04.000Z
- Updated: 2026-08-31T18:31:04.000Z
- Description: How Satisfactory runs a planet-sized factory on Unreal Engine: hand-crafted world streaming, the Significance Manager, abstracted conveyor items and rail-graph trains.
- Author: ENGN GAME STUDIO LLC
- Tags: Satisfactory, Articles

### Engine & Tech Stack

- **Engine / language:** Unreal Engine (shipped on UE4, later upgraded to UE5), with gameplay in C++ on Unreal's Actor/Component framework.
- **Map representation:** one large, hand-crafted 3D open world (not procedural), streamed with Unreal's level streaming and World Partition rather than a tile grid.
- **Build system:** factories, belts and pipes snap onto the world, each backed by an Unreal Actor.

### Core AI & Decision Making

- **Creatures:** wildlife uses lightweight Unreal behaviour (roam, flee, attack) on the NavMesh; there is no deep NPC society, the simulation is logistics rather than agents.
- **Dispatch:** trucks and tractors follow player-recorded paths on autopilot, while trains route over the rail-network graph using block signals.

### State Management & Data Architecture

- **Model:** Unreal Actors and components; world state is the sum of placed buildings, belts, pipes, the power grid and inventories.
- **Belt items:** items on conveyors are not individual Actors, they use a compact, abstracted representation so long belt chains stay cheap.
- **Persistence:** the entire world (every building, item and vehicle) is serialised into the save.

### Tick Scheduling & Performance Tricks

- **Significance Manager:** Unreal's Significance Manager lowers update rates for distant, less-important machines so far-off factory sprawl costs less.
- **Bulk simulation:** conveyor and pipe contents are advanced in bulk rather than per-item-per-frame, and dedicated servers offload simulation from clients.

### Pathfinding & Spatial Systems

- **Creatures:** Unreal **NavMesh** pathfinding.
- **Trains:** graph pathfinding over the rail network with block signals; road vehicles follow recorded splines.
- **Spatial:** World Partition and spatial hashing drive culling and streaming across the large map.