By default, players must defeat AI opponents repeatedly to win individual cards. A card unlocker is a save file modification or a registry patch. It alters the game data to immediately place three copies of every single card into your virtual trunk. Why Players Use Unlockers

The Yu-Gi-Oh! wiki, Yugipedia, also documents that there are over 10,000 unlockable cards in some games, and beating certain levels or duelists will unlock new booster packs or reward the player with rare cards . This highlights the extensive nature of these games and why players might seek unlockers.