So this is where
Marvel Trading Card Game gets complicated. Starting the game is easy. When you first load it, you'll see that you have three game save slots. Choose one of the "New Game" slots. Professor X will then show you a few screens that tell you about the story of the game, after which he asks if you would like to play the Tutorial. I would highly recommend going through the tutorial just so you're not completely lost.
After you go through the Tutorial, you're given the option to choose Hero or Villian. Now you would think that these would be opposite games, as you obviously wouldn't have the same path to take as a villain that you do as a hero. Well that's true in a way. Both paths have the same chapters to go through, the same or very similar opponents, but they have different Card Packs to unlock.
As you beat missions and solve the challenges, you unlock Card Packs that you can buy. For each level you beat and each challenge you solve, you get points that you can spend to unlock Play Mats and Card Packs. Play Mats simply change your background. Card Packs give you more cards to add to your deck. The cards in Marvel Trading are the one really great thing about it. You get to see many, many cards of your favorite Marvel heroes, such as Spiderman, Iron Man, and She-Hulk, and your favorite villains including Dr. Doom, Green Goblin, and Mystique. Both heroes and villains have team affiliations, allowing them to work with their team members for a team attack, which is much stronger than a normal attack.
You also have the option of playing Marvel Trading as a multiplayer game. You can play it wirelessly with a local player or you can play against someone online.