Dark Duel Stories does not totally conform to the rules of the Official Card Game. This includes many cards having different effects, or having their effects removed altogether, including, but not limited to, Jirai Gumo; this means that some Monster cards with effects in the OCG may not have any effects at all in this game, whether positive or negative.
Rather than having flip effects or passive effects like many cards in the OCG, most cards seem to only be able to activate their effects on the first turn they are played. Many cards seen only in this game (the 'Creatable' cards) also have Type and/or Attribute that do not match their appearance at all. While this can also be seen in the official card game, this happens much more often in this game.
During gameplay there is more than one way to win. A player may win by decreasing the opponent's life points to zero, forcing your opponent to run out of cards (have them unable to draw a card at the start of their turn), or by having all five pieces of Exodia in your hand.
In order to duel, a player's Deck must contain 40 cards and be under their current Duelist Level. If the Deck is over/under 40 cards or over the Deck limit cost, the player will not be able to duel until the error is fixed.