/// <summary>
/// Allows the game to perform any initialization it needs to before starting to run.
/// This is where it can query for any required services and load any non-graphic
/// related content. Calling base.Initialize will enumerate through any components
/// and initialize them as well.
/// </summary>
protected override void Initialize()
{
var worldBuilder = new WorldBuilder();
var playerSystem = new PlayerSystem(_entityFactory);
_world = worldBuilder.AddSystem(new SpriteRenderSystem(GraphicsDevice))
.AddSystem(playerSystem)
.AddSystem(new EnemySystem())
.AddSystem(new ShipBulletMovementSystem())
.AddSystem(new ShipBulletAlienCollisionSystem())
.Build();
_entityFactory.World = _world;
_scalingBatch = new SpriteBatch(GraphicsDevice);
_scalingTarget = new RenderTarget2D(GraphicsDevice, 224, 256);
base.Initialize();
}