This game taught me to be good at yugioh. For anyone who doesnt know how to progress:
You beat each opponent that appears in duel world once each, until something happens.

Beating them 5 times unlocks opponents in the world championship mode.

Beating world championship opponents 5 times, or progressing through the game, unlocks more packs and more opponents for world championship mode. If you want to unlock anything, you will NEED a guide (I used gamefaqs)

I loved yugioh, so I loved this game. If you don't love yugioh, then don't bother.