A document declares an entry scene. Each scene owns its entities, active camera, environment, and optional music and HUD. A scene transition changes which scene the session runs.
AETHER’s repeated architecture illustrates a scene assembled from reusable objects. The image alone does not identify which objects are prefabs. Capture source.
Compose an entity
An entity’s ID is its stable identity. Its name is a label. Components supply appearance, physics, camera, sound, or particles. Behaviors supply actions such as collection, triggers, spawning, health, or scripts.
In 2D, place sprites and tilemaps with the entity transform. Add a body and collider when an object must move or participate in collisions. In 3D, transform3d supplies position, quaternion rotation, and positive scale. Add a primitive or prepared model independently of its collider. Visible geometry does not automatically create physics.
Use the scene tree to select, duplicate, rename, reparent, or delete objects. Group related entities with parent IDs. A physics hierarchy has stricter rules than a decorative hierarchy: scale and competing pose owners are rejected. Physics explains the distinction.
Tag and parameterize
tags identify groups such as guard or collectible. props hold JSON data such as a door’s required key. Scripts can query tags and read properties without depending on display names.
{
"op": "update_entity",
"entity_id": "door",
"set": {"tags": ["gate"], "props": {"requiredKey": "amber"}}
}
This is an edit_native_game operation, not a complete document. It replaces each supplied metadata field. A top-level null removes the field. Nested null remains JSON data. Tags and properties require 2D schema 4 and are supported in 3D schema 3.
Reuse a prefab
Keep repeated gameplay objects in prefabs and spawn them through a behavior or script. Each instance has its own runtime state. A 3D prefab declares a root, child entities, and external asset and scene references. A template-only entity is excluded from the initial active scene.
Use retained construction when you also need generated placement, stable explicit construction keys, per-instance overrides, and rebuild previews. Resetting an override, detaching a generated entity, and deleting it have different effects on future rebuilds.
A scene transition discards the previous scene’s behavior state. Persist progress explicitly with save commands when it must survive a new session.