How to Make Open World Games
Writer
Baha Pirani From Blacave
Article Date: 2025 September 04
Note: This article has final exam, by passing it you can get 10 Black Points (1$), so don't forget to read it until the end and answer the exam at the bottom of the article.
How to Make Open World Games
So, you want to create an open world game? The idea of building a vast, living landscape for players to explore is one of the most exciting challenges in game development. While massive studios spend years and millions of dollars on titles like The Elder Scrolls or Grand Theft Auto, you can start your journey with the same core principles.
This guide will break down the two foundational pillars for any open world: creating the map and populating it with AI agents. We'll focus on the "what" and "how" for beginners, using accessible tools and concepts.
1 - Building Your World - The Map is the Canvas
The map is the heart of your open world. It’s not just a pretty background; it’s the stage for every player adventure. For beginners, the key is to start simple and scale up.
Planning and Design: Paper Before Pixels
- Define Your Vision: Is your world a post-apocalyptic wasteland, a vibrant fantasy realm, or a bustling cyberpunk city? The theme dictates everything.
- Sketch a Layout: Draw a rough map. Identify key biomes (forests, mountains, rivers, cities). Use the "Point of Interest" (POI) method. Place major landmarks—a central city, a ominous tower, a winding canyon—and then connect them with interesting, non-linear paths. Avoid a boring, empty grid.
- Create a Flow: Guide the player naturally. Use hills to block sightlines, rivers to channel movement, and landmarks as visual anchors to pull players toward secrets.
A simple terrain
A simple terrain
2 - Choosing Your Tools and Building the Terrain
Most modern game engines have powerful, beginner-friendly terrain tools.
- Unity: Excellent for beginners, with a gentle learning curve and a massive asset store. Its terrain system is visual and intuitive. You can also use a premium tool called Gaiea to make realistic landscapes.
- Unreal Engine: Known for stunning graphics out of the box. Its landscape tool is incredibly powerful for large worlds. You can also use premium tools, for instance Brushify to make realistic landscapes.
Basic Terrain Sculpting:
- Raise and Lower: Start by shaping the hills and valleys you sketched on your paper map.
- Smooth and Flatten: Use these tools to create plateaus for buildings or flat paths for roads.
- Sculpting Tips: Create variety. Don’t make all your mountains perfect cones. Use a soft brush to create rolling hills and a hard brush for sharp cliffs.
3 - Painting the World with Textures and Foliage
A grey-boxed world is functional, but a painted world is immersive.
- Texture Painting: Apply different ground materials like grass, dirt, rock, and sand. Start with a base layer (e.g., grass) and then paint dirt on paths, rock on mountainsides. This tells a story of where people and creatures walk.
- Placing Foliage and Props: Use the built-in foliage and painting tools to scatter trees, bushes, rocks, and flowers across your landscape. Vary the size and rotation to make it look natural. This is a fast way to take a bare landscape from "empty" to "lived-in."
A production ready terrain/landscape
A production ready terrain/landscape
4 - Bringing the World to Life - AI and Agents
A beautiful but empty world feels dead. AI agents—like villagers, monsters, and wildlife—are what make your world feel dynamic and alive.
Understanding AI for Beginners: It's Not Magic
In games, AI (Artificial Intelligence) doesn't mean creating a sentient mind. It's about creating the illusion of intelligence through simple rules and behaviors.
Core AI Behaviors: The Building Blocks
- Wandering: An NPC or creature moves randomly within a defined area. This is perfect for wildlife like deer or background townfolk.
- Patrolling: An agent follows a fixed path, like a guard walking between two posts. You define the path using a set of points in the world.
- Chasing and Fleeing: This gives your world conflict. When the player enters a certain range (the "trigger radius"), an enemy can chase them, or a prey animal can flee.
5 - Implementing Basic AI: The "State Machine"
A simple way to think about AI is with a State Machine. Your agent can only be in one "state" at a time.
- Idle State: The agent is standing or wandering casually.
- Alert State: The agent has seen or heard the player. It might stop and look.
- Chase State: The agent moves quickly towards the player to attack.
- Flee State: The agent moves quickly away from the player.
- Your code simply switches between these states based on conditions (e.g., "IF player is seen, THEN switch from Idle to Chase").
An example of state machine system for AI and NPCs in Unreal Engine
6 - Making AI Feel Believable
Simple touches make a huge difference:
- Animation: An NPC that just slides across the ground is creepy. Connect your AI states to animations: a walk cycle for patrolling, a run cycle for chasing.
- Audio: Add footstep sounds, ambient creature noises, or alert barks. Sound is half the immersion.
Frequently Asked Questions (FAQ)
I'm a complete beginner. Which engine should I start with, Unity, Unreal or Godot?
All of them are great. Unity often has a gentler initial learning curve for coding (using C#) and is very flexible. Unreal Engine uses C++ but also has a visual scripting system called Blueprints, which is fantastic for beginners who want to prototype without deep coding. Godot is growing, it offers many tools and also a language called GD script (Godot script) which is similar to Python, also you can write codes with C# and also change the source code with C++, and you can find many tutorials on this engine. Try the beginner tutorials for both and see which interface you prefer.
How big should my first open world map be?
Much, much smaller than you think! Aim for a playable area that takes 2-5 minutes to run across, not 2 hours. A detailed, hand-crafted valley with 3 Points of Interest is a perfect starting project. Quality and interesting content always beat sheer size.
My game runs slowly with a large map and lots of trees. What's wrong?
This is a performance issue. You need to implement Level of Detail (LOD). LOD means that objects far away from the player are rendered with simpler, lower-polygon models. Unity, Unreal, Godot and many other game engines have built-in LOD systems to help with this. Also, use the engine's occlusion culling tools.
How do I make my NPCs have conversations or go to work and sleep?
This is done by creating a schedule and enhancing the State Machine. You can assign NPCs different states (e.g., "SleepState," "WorkState," "SocialState") and switch between them based on an in-game clock. It's more complex, but it builds directly on the basic "Wander" and "Patrol" behaviors.
What is "procedural generation" I keep hearing about?
Procedural generation uses algorithms to create content automatically. Instead of manually placing every tree, you can write a rule like "place trees randomly, but not too close together." It's a powerful technique for creating massive worlds, but it's an advanced topic. We recommend mastering hand-crafting your world first so you understand design principles.
References
Unity Beginner Terrain Tutorial
How to add a terrain in Unreal Engine
Writer
Baha Pirani From Blacave
