# Function: createEntity()

> **createEntity**\<`Vars`\>(`id`, `variables`): [`SimpleObject`](../type-aliases/SimpleObject.md)\<`Vars` & [`AssertNoOptionals`](../type-aliases/AssertNoOptionals.md)\<`Vars`\>\>

Defined in: [packages/core/src/gameObjects/fabric.ts:48](https://github.com/laruss/react-text-game/blob/37ebb1fd49045bfbb1d2a2fa96b8f14a2f8c2644/packages/core/src/gameObjects/fabric.ts#L48)

Convenience factory that wraps [SimpleObject](../type-aliases/SimpleObject.md) creation.

This function mirrors the fabric-style APIs used for passages so entity
authors can define state in plain objects and still get reactive behaviour.
The created entity is registered with the game engine via the
`BaseGameObject` constructor and exposes its variables as direct
properties.

**IMPORTANT:** All properties in `variables` must be required (non-optional).
The `AssertNoOptionals` type enforces this at compile time. Optional properties
are not supported because the Proxy-based implementation cannot distinguish
between undefined optional values and missing properties. If you need optional-like
behavior, use explicit `undefined` with a union type (e.g., `field: undefined as string | undefined`).

## Type Parameters

### Vars

`Vars` *extends* [`InitVarsType`](../type-aliases/InitVarsType.md)

## Parameters

### id

`string`

Unique identifier used for registry lookups and persistence.

### variables

`Vars` & [`AssertNoOptionals`](../type-aliases/AssertNoOptionals.md)\<`Vars`\>

Initial reactive state for the entity. Nested objects and
arrays are supported and proxied. Must not contain optional properties.

## Returns

[`SimpleObject`](../type-aliases/SimpleObject.md)\<`Vars` & [`AssertNoOptionals`](../type-aliases/AssertNoOptionals.md)\<`Vars`\>\>

A `SimpleObject` instance that can be used anywhere a
`BaseGameObject` is expected.

## Example

```typescript
// ✅ Correct - All properties are required
const player = createEntity('player', {
  health: 100,
  name: 'Hero',
  inventory: [] as string[]
});

// ✅ Correct - Use explicit undefined for optional-like behavior
const character = createEntity('character', {
  name: 'NPC',
  quest: undefined as string | undefined
});

// ❌ Wrong - Optional properties will cause compilation error
const player = createEntity('player', {
  health: 100,
  mana?: 50  // TypeScript error: optional keys not allowed
});
```