Inside Unreal and Unity: Procedural Content Generation Workflows That Scale

In modern game development, procedural content generation plays a central role. It empowers creators to build vast, dynamic worlds without manually placing every object. In this article, we’ll explore how two of the biggest engines Unreal Engine and Unity, enable scalable workflows. We’ll break down practical steps, give insight into challenges, and point to a smart asset-store tactic as part of your workflow.

Why Procedural Content Generation Matters

When you build a game world manually, each tree, rock, building placement takes time. With procedural content generation (PCG), algorithms fill large areas, apply variations, and integrate into your level-design pipeline. Research shows that PCG allows developers to shift focus from low-level asset placement to high-level design rules.

In a typical indie project, content creation often takes 50-70 % of production time. By adopting a PCG workflow, you reduce that effort substantially. It also improves replayability: every playthrough can present fresh layouts, helping extend the lifetime of your game.

From a scalability perspective, whether you build an open world, a procedurally generated dungeon, or modular levels for mobile, PCG offers a reusable, efficient pipeline.

High-Level Workflow Comparison: Unreal vs Unity

Unreal Engine Workflow

In Unreal Engine, the built-in framework for PCG is called the Procedural Content Generation Framework (PCG). According to the documentation:

• The PCG graph allows you to define points in 3D space, filter them, and spawn meshes or assets based on attributes. Epic Games Developers+2Epic Games Developers+2
• It integrates with level streaming, landscape, foliage tools and meshes, enabling large, open-world generation in a semi-automated way. Epic Games Developers+1
• The PCG system is built for speed and iteration: changes to the graph reflect almost immediately in the editor viewport. Epic Games Developers

Why this workflow scales well:

• Designers can iterate on rules rather than repositioning every item.
• Reuse of graph templates and assets across levels becomes viable.
• Integration with Unreal’s high-fidelity tech (Nanite, Lumen) means even large worlds remain performant. (Though hardware requirements may be higher.) arXiv+1

Common steps in an Unreal PCG workflow:

1. Enable the PCG plugin in your project. Epic Games Developers
2. Create a PCG Graph asset, define generation nodes (point sampling, filters, mesh spawners).
3. Connect the graph to a PCG Component in the level.
4. Define asset pools (e.g., building modules, vegetation types) and rules for placement (density, steepness, seed).
5. Iterate: tweak parameters, preview results, refine.
6. Integrate with streaming/LOD/fallback systems to support target platforms.
7. Use modular asset sets so that the rule-graphs can reference them, enabling variation.

Unity Workflow

Unity does not have a single built-in “PCG framework” on par with Unreal’s, but it supports procedural generation via scripting, tools and plugins. Some workflow highlights:

• Unity’s documentation on procedural patterns using Tilemaps shows how 2D (and by extension 3D) content can be generated using rule-sets. Unity
• In Unity, you often work via C# scripts or custom editor extensions to generate meshes, terrains, or place asset prefabs at runtime or in the editor. Medium
• Open-source frameworks (for example “OrganicaWild”) demonstrate PCG pipelines inside Unity: graph grammars, noise functions, search-based methods for world generation. GitHub

Why this workflow can scale, with discipline:

• Unity’s scripting flexibility means you can tailor PCG systems exactly to your need.
• Because Unity is widely used in mobile and indie dev, PCG can reduce content-creation cost significantly.
• If you build modular assets and tile/prefab sets, the rule-based generation means fewer manual placements.

Common steps in a Unity PCG workflow:

1. Define your modular asset pool: prefabs for terrain chunks, props, environmental pieces.
2. Create scripts/editor tools that sample noise, spawn prefabs, apply rules (height threshold, density, adjacency).
3. Use perlin noise, fBM, cellular automata for terrain / layout variation. Medium+1
4. Integrate the generation on level load or editor-time for faster iteration.
5. Automate LODs, streaming or chunking for large worlds (if targeting open world).
6. Monitor and optimize: too many objects, overdraw, or heavy meshes kill performance.

Key Elements of a Scalable Workflow

No matter which engine you pick, these elements help your PCG pipeline scale.

Modular Asset Design

Make your assets modular: buildings broken into sections, terrain chunks sized consistently, props with shared materials. This lets your generation system swap pieces easily and vary layouts without manual tweaks.

Rule-Based Variation

Set up rules for asset placement: e.g., trees only where slope < 0.3, buildings aligned to roads, rocks with random rotation. In Unreal’s PCG Graph you can filter by steepness and density. In Unity you embed such logic via scripts or frameworks.

Parameter-Driven Generation

Expose parameters like seed, density, scale, noise amplitude. Your designers should be able to experiment without code changes. This makes your pipeline more designer-friendly.

Streaming and Performance

For large worlds, you must stream chunks, control LODs, and optimize draw calls. Unreal supports landscape streaming and large world tools; Unity requires you to build that explicitly but it’s feasible.

Iteration and Tooling

Your workflow should support fast iteration. Generation should be previewable, tweakable in editor, and feed back quickly so design becomes creative rather than laborious. Unreal’s PCG Graph with real-time preview helps. Unity’s custom editor windows and play-mode generation assist.

Asset Store Integration

Even with PCG, you don’t always want to build every asset yourself. Having a good source of reliable modular 3D assets helps. For instance, the Animatics Assets Store (a source I’ve used) offers free 3D game asset sets that can plug into both Unreal and Unity pipelines. When you integrate these assets into your modular asset pool, your PCG system gains more variation without extra modelling. This isn’t a paid endorsement—it’s simply a practical tip: coupling PCG workflows with a free, asset-rich store speeds up production and keeps budgets in check.

Engine-Specific Tips & Pitfalls

Unreal Engine Tips

• Leverage the PCG Framework: Use template graphs so you don’t recreate logic from scratch each time.
• Combine PCG with the Open World Tools: The foliage mode, landscape system, and PCG integration permit large scenes. Epic Games Developers+1
• Keep an eye on hardware: High-fidelity visuals (Nanite, Lumen) demand performance budgets. PCG may generate many objects; you’ll still need to manage draw calls, culling, streaming.
• Version control your graphs and assets: PCG graph revisions matter when you’re iterating heavily.

Unity Tips

• Start with a clear architecture: Define how your generation scripts will run (editor vs runtime), how assets get referenced, how layouts are defined.
• Use noise functions smartly: Perlin noise, fractal Brownian motion (fBM) and cellular automata are common in Unity for terrain/level generation. Medium+1
• Consider chunking your world: If you generate very large scenes, divide into manageable pieces with pooling/unload mechanics.
• Monitor performance: Because Unity doesn’t always auto-cull or stream assets for you in PCG systems, you must be proactive about LODs and object counts.

Measuring Success: Metrics That Matter

When your workflow scales, how do you measure that? Here are some useful metrics and facts:

• Time to prototype a level: If you go from blank to playable in two hours rather than eight, PCG is working.
• Asset reuse rate: How many times does one modular asset appear in different arrangements? Higher reuse means less manual work.
• Variation count: Count the unique layouts or procedural variants your system generates.
• Performance headroom: Even with PCG, your build must run at target framerate on target platform. Unreal and Unity both show that energy and performance cost varies by engine. arXiv

A research paper on PCG-for-games concluded that focusing on algorithms for believable content rather than low-level plumbing leads to higher productivity.

Bringing It Together: Example Workflow

Here’s how you might stitch the above pieces in a small-team indie game using Unity (but the same logic applies to Unreal):

1. Decide world scope: e.g., procedurally generated forest plus campout area.
2. Build or acquire modular assets: trees, rocks, logs, terrain chunks (from your asset store).
3. Create a “TerrainGenerator” editor script: uses Perlin/fBM noise to define heightmap, spawns terrain chunks accordingly.
4. Apply “FoliageSpawner”: sample each terrain chunk, place tree prefabs using density rules, rotation variation, slope thresholds.
5. Add “PointOfInterestGenerator”: at random seed positions spawn a cave entrance prefab or cabin prefab.
6. Expose parameters: seed, tree density, terrain roughness. Design team tweaks live in editor.
7. Playtest: check object counts, LOD transitions, VRAM usage.
8. For the next level set: re-seed, shuffle asset variants, run again — the layout is fresh, but asset pipeline and rules stayed the same.

In Unreal, you’d instead build a PCG Graph asset that defines the point generation, filters, mesh placement; use modular building blocks in the Content Browser; preview in editor; then hook into streaming landscape system for large-scale levels.

Final Thoughts

Scaling a game’s world is less about manual placement and more about smart rules, iteration, and modular assets. With procedural content generation properly implemented, you free your team to think creatively rather than tediously. Here’s your take-away checklist:

• Pick your engine (Unreal or Unity) and lean into its workflow strengths.
• Build your modular asset library early. Use asset store resources to speed this up.
• Define your procedural rules: how assets spawn, how terrain forms, how variation arises.
• Expose parameters and support fast iteration.
• Plan for performance: streaming, LOD, object count.
• Measure success: time saved, asset reuse, variant count, performance headroom.

By investing in this flow, you’ll be able to handle bigger worlds, more variation, and less manual content drudge. Whether you’re building an open world in Unreal or a procedurally generated mobile experience in Unity, workflows anchored in PCG can make scaling feel natural. Use the tools, reuse the assets, iterate fast—and let algorithms do the heavy lifting so your designers stay creative.