SIECS

SIECS is a small archetype ECS library with a compact C23 API, C++23 wrapper, reflection, modules, and an optional REST explorer for tools.

The public user API is exposed by:

The public header is <siecs.h> in all supported language integrations.

The current API is centered around:

Concept	Role
World	Owns all ECS storage. Create with ecs_init(), destroy with ecs_fini().
Entity	ecs_entity_t handle created by ecs_new().
Component	Registered data type identified by ecs_component_t.
Query	Cached matcher over archetype tables.
Iterator	Batch iterator returned by ecs_query_iter().
System	Scheduled query callback run by ecs_progress().
Observer	Callback triggered for built-in or custom events.
Module	Import unit that groups components, systems, and observers.
Relation	Component that stores an entity target, such as ChildOf.
Resource	One typed value stored on the world, not on entities.

What to read first

1. Getting started for a complete minimal program.
2. ECS theory for the storage and iteration model.
3. Components and resources for data modeling.
4. Queries for iteration with ecs_iter_t.
5. Systems for scheduled logic.
6. Observers and events for EcsOnAdd, EcsOnRemove, EcsOnSet, and custom events.
7. Performance guide before writing hot-path code.
8. API reference for the public symbols.