player_state.dart

enum PlayerState { regular, duck, left, right, jump, hit, shoot }

...

@override
  Future<void> onLoad() async {
    await super.onLoad();

    await _loadCharacterSprites();

    position = Vector2(size.x, gameRef.size.y - 10);
  }
  
...

Future<void> _loadCharacterSprites() async {
    final regular = await gameRef.loadSpriteAnimation(
        'spritesheet.png',
        SpriteAnimationData.sequenced(
          amount: 7,
          textureSize: Vector2(63.4, 130.0),
          stepTime: 0.15,
          loop: true,
        ));

    final right = await gameRef.loadSpriteAnimation(
        'left.png',
        SpriteAnimationData.sequenced(
          amount: 5,
          textureSize: Vector2(63.4, 130.0),
          stepTime: 0.20,
          loop: true,
        ));

    final left = await gameRef.loadSpriteAnimation(
        'right.png',
        SpriteAnimationData.sequenced(
          amount: 5,
          textureSize: Vector2(63.4, 130.0),
          stepTime: 0.20,
          loop: true,
        ));

    final jump = await gameRef.loadSpriteAnimation(
        'jump.png',
        SpriteAnimationData.sequenced(
          amount: 3,
          textureSize: Vector2(70.4, 130.0),
          stepTime: .2,
          loop: false,
        ));

    final hit = await gameRef.loadSpriteAnimation(
        'hit.png',
        SpriteAnimationData.sequenced(
          amount: 3,
          textureSize: Vector2(73.4, 110.0),
          stepTime: 0.20,
          loop: false,
        ));

    final shoot = await gameRef.loadSpriteAnimation(
        'shoot.png',
        SpriteAnimationData.sequenced(
          amount: 3,
          textureSize: Vector2(90.4, 110.0),
          stepTime: 0.20,
          loop: false,
        ));

    final player = SpriteAnimationGroupComponent<PlayerState>(animations: {
      PlayerState.regular: regular,
      PlayerState.left: left,
      PlayerState.right: right,
      PlayerState.jump: jump,
      PlayerState.hit: hit,
      PlayerState.shoot: shoot,

      //PlayerState.duck: duck,
    }, current: PlayerState.regular);
    animations = player.animations;

    current = PlayerState.regular;
  }