Fast Prototyping Game Mechanics with ECS

In this series, I want to share my experience using Entity Component System (ECS) to quickly prototype game mechanics. My goal is to explore ECS patterns, understand their strengths, and apply them to design expressive game behavior.

I use Godot and GDScript for implementation. My lightweight ECS realization allows me to:

• Quickly test new ECS ideas and observe their impact on prototyping.
• Use Godot’s IDE for data configuration and visualization.

🎮 Projects

• Locomotion Prototype (initial test)
• Asteroids Clone (current project)

The first was a simple motion test. The Asteroids project expands into combat logic, state switching, and time-based effects. I’ll return to Locomotion later to refine it with lessons learned.

🧠 System Categories

From my experience, ECS systems fall into 3 types:

1. Trigger Systems
   Detect conditions and attach/remove TagComponents.

2. Logic Systems
   Query DataComponents (filtered by Tags), update data, and sometimes add new components.

3. General Calculation Systems
   Transfer or compute values between components. Example: update Velocity based on Thrust.

🧪 Rules I’m Testing

• Each system should update only one type of data.
• Each entity should contain only one instance per component type.
• Systems should contain minimal conditional logic.

This helps reduce complexity and encourages clean data flows.

🛠 ECS Features (Roadmap)

• Component Hierarchy: Components are entities themselves. e.g. BuffComponent can contain a LifetimeComponent.
• Component Relations: Define parent-child behavior, like “follow” or positional offset.
• Component Chains: When a component is removed, define which component to add next (useful for state machines).
• Multiple Component Instances: With roles or relations (e.g., Weapon(primary) and Weapon(secondary)).
• Message Queue: Entities send messages to systems, processed in batch during update.

🧰 Visualization & Tooling Ideas

• Render entities and components inside the Godot editor.
• Live sync of position/rotation.
• Load map data into the ECS world.
• Feature logger: log which systems update which entities.
• Separate visual and logical components (possibly different node hierarchies).

🧩 Component Types

DataComponent
Holds data like position, velocity, health.

TagComponent
Stateless marker flags:

• Type: Player, Enemy, Item
• State: OnStage, Visible, Active
• Action: NextState, DestroyAfterHit

I aim to replace control-flow (if trees) with data-driven logic using these tags.

🔗 References & Resources

• Entity relationships in ECS
• Game design for ES
• Adventures in Data-Oriented Design
• Why vanilla ECS is not enough
• Unity ECS Samples
• Data-Oriented Design repo
• Practical DOD Examples (PDF)
• Cognitive Dimensions of Notations

Thanks for reading. I’d love to hear how others structure systems and handle state transitions with ECS. Feel free to reach out or suggest experiments!