Here's a breakdown:
* The Rule: The game rule states that if a player's Deck runs out of cards, that player loses the duel.
* Why it happens: Running out of cards means you can't draw anymore, and therefore, you can't continue playing.
* No Exceptions: There are no exceptions to this rule. Even if you have cards in your hand or field, you lose.
Important Note:
* Shuffling the Graveyard: At the end of each of your turns, you must shuffle your Graveyard into your Deck if it's empty. This ensures that you'll always have cards to draw, but it also means you'll likely be drawing your own cards again, including those that may be weak or unhelpful at that moment.
* Deck Construction: It's important to build your deck carefully to avoid running out of cards. Consider including a sufficient number of cards to keep your Deck full and balanced.
Let me know if you have any other questions about Yu-Gi-Oh! rules!