Building Worlds with Procedural Generation
Have you ever marveled at the seemingly endless, unique worlds in games like Minecraft or No Man's Sky? Or felt the thrill of a dungeon in Hades that’s different every single time you play? The magic behind these experiences is a powerful concept called Procedural Content Generation (PCG).
In short, PCG is the art of teaching a computer the rules to create content, and then letting it generate countless variations on its own. It's a partnership between human creativity and algorithmic power, and it’s changing how we build digital worlds.
Why Generate Content instead of Crafting it?
Early games like Rogue (1980) used PCG because memory was measured in kilobytes and storing a whole world was a fantasy. Today, the motivations are a bit more ambitious:
- Endless Replayability: New levels, maps, and challenges every time you play games like Hades.
- Massive Scale: Create a world the size of a planet in No Man's Sky without needing a massive art team to painstakingly place every single rock. (They will thank you.)
- Development Efficiency: Automate the boring bits, freeing up designers to focus on more important things, like the physics of a hero’s cape.
But it’s not a magic bullet. Poorly implemented PCG leads to the dreaded "procedural oatmeal"—thousands of mathematically unique bowls of beige, flavorless mush. The goal isn't just to make things different, but to make them interestingly different.
This means treating PCG as a design philosophy. To teach a computer to make a "fun level," a designer must first have a very serious, soul-searching moment to codify what "fun" actually means. The algorithm then becomes an extension of that slightly-less-confused designer's vision.
For more check out: Practical Procedural Generation for Everyone (GDC Talk), The Power of Procedural Generation in Gaming, Pros and Cons of Procedural Generation (Reddit)
A Tour of the Algorithmic Toolkit
Designers have a menu of algorithms to choose from, each with its own special talent for creating structured chaos.
Perlin & Simplex Noise
This is the go-to for making things look like nature made them instead of a machine. Noise functions create smooth, organic patterns, perfect for generating terrain, coastlines, and clouds that don't have suspiciously straight edges. It’s for when you need a mountain range that looks natural and not like you just sneezed on your keyboard.
- See it in: Minecraft, Terraria, Worms
- More: Perlin noise (Wikipedia), Generating Worms-style Terrain with Simplex Noise
Cellular Automata (CA)
Imagine a grid of cells, each following a few simple rules based on its neighbors. You start with random static, press "go," and come back to find it has either carved out a masterpiece of a cavern or a single, impenetrable block. It’s an emergent, bottom-up approach to creating beautifully organic cave systems.
- See it in: Dwarf Fortress, Terraria
- Learn more at: The Cellular Automaton Method for Cave Generation
Binary Space Partitioning (BSP) Trees
This method recursively splits an area, places a room in each piece, then dutifully connects them with corridors. It's the responsible adult of PCG algorithms, guaranteeing your dungeon rooms won't ever overlap, which is more than you can say for your calendar appointments. It creates very structured, architectural layouts.
- See it in: Countless roguelikes. (It was also the 3D rendering workhorse for the original Doom!)
- For further reading: Dungeon generation using BSP trees, BSP, and games (Polycount)
L-Systems (Lindenmayer Systems)
Originally designed by a biologist to model plant growth, because obviously the first thing you think when looking at a fern is, "I bet I can make a city map with that." L-Systems use rules to create intricate, branching structures, making them perfect for generating trees, river networks, and yes, even city streets.
- See it in: Often used behind the scenes to create libraries of unique trees and plants for game worlds.
- For further reading: Procedural content generation: L-Systems, Game Mechanics Integrated with a Lindenmayer System
Wave Function Collapse (WFC)
A newer, powerful algorithm that works like a very stressed-out Sudoku puzzle. It arranges tiles on a grid based on rules about which tiles can be neighbors. When it works, it's genius, creating highly detailed maps that look hand-authored. When it fails, it throws a digital tantrum (a "contradiction") and you have to start over.
- See it in: Bad North, Townscaper, Caves of Qud
- For further reading: WaveFunctionCollapse (Original GitHub), Wave Function Collapse in Bad North (YouTube), How Townscaper Works
At a Glance: Choosing the Right Tool
| Algorithm | Best For Creating... | Key Strength | Example Games |
| Noise Functions | Natural Terrain, Textures, Heightmaps | Smooth, organic, and suspiciously natural | Minecraft, Terraria |
| Cellular Automata | Organic Caves, Natural Formations | Creates complex patterns from simple rules | Dwarf Fortress, Terraria |
| BSP Trees | Structured Rooms & Corridors | Guarantees no awkward overlapping rooms | Roguelikes, Doom (1993) |
| L-Systems | Branching Structures (Plants, Roads) | For when your world needs more fractals | (Asset generation) |
| Wave Function Collapse | Detailed, Locally Coherent Tilemaps | Feels hand-authored, if it doesn't fail | Bad North, Townscaper |
Not Just for Games: A Universal Grammar of Creation
The principles of PCG aren't confined to gaming. They are quietly building the world all around us.
- Visual Effects: Software like Houdini uses proceduralism to create complex simulations for film, like collapsing buildings or explosions that look realistically expensive.
- Urban Planning: Tools like CityEngine generate vast, detailed 3D city models to visualize traffic flow and zoning laws. Yes, the same logic that builds your fantasy dungeon may also be designing a sensible suburb. Try not to think about that on your commute.
- Generative Art: Artists design algorithms that create unique artworks, proving that even a soulless machine can have an "abstract phase."
There's a "universal grammar" for procedural creation. Whether you're building a game level or a skyscraper, the core logic is strangely similar.
For further reading: A Survey of Procedural Techniques for City Generation, Generative art (Wikipedia)
The Next Frontier: AI-Assisted Design
The field is now being supercharged by machine learning in an approach called PCGML. Instead of designers writing rules, they now curate data and train an AI to learn the patterns of good design, outsourcing the hard work to our new silicon assistants.
Large Language Models (LLMs) are a huge part of this. They can generate text for quests and characters, but also the code for level layouts. Imagine prompting an AI: "Generate a small, defensible village, but make it look like the locals are having a bit of a tough century." The future is here, and it's taking notes.
The Future is Collaboration
Procedural generation is moving away from being a "black box" that spits out content. The future is about co-creative tools, where an AI acts as an intelligent assistant that never needs a coffee break.
The goal isn't to replace human creativity but to augment it. Designers set the vision and hand-craft the important moments. The procedural systems then fill in the details, ensuring the world is not only endlessly variable but also aligned with the creator's intent. It's a beautiful partnership, where the designer gets the creative credit, and the AI gets... more electricity, probably.
