FromJson with Object in Object

fantasy.dart

import 'package:news/models/player.dart';

import 'game.dart';

class Fantasy {
  String id;
  String name;
  DateTime openAt;
  DateTime closeAt;
  Game game;
  List<PLayer> players;
  bool open;
  bool active;

  Fantasy({
    this.id,
    this.name,
    this.openAt,
    this.closeAt,
    this.game,
    this.players,
    this.open,
    this.active,
  });

  factory Fantasy.fromJson(Map<String, dynamic> json) {
    return Fantasy(
      id: json['_id'],
      name: json['name'],
      openAt: DateTime.parse(json['openAt']),
      closeAt: DateTime.parse(json['closeAt']),
      game: json['game'], //COMO FAZER ISSO AQUI?
      players: List.from(json['players']),
      open: json['open'],
      active: json['active'],
    );
  }
}

game.dart

import 'package:news/models/article.dart';

class Game {
  String name;
  String slug;
  List<Article> articles = [];

  Game({this.name, this.slug});

  factory Game.fromJson(Map<String, dynamic> json) {
    return Game(
      name: json['name'],
      slug: json['slug'],
    );
  }
}