It is a tv show as well. the show is quite hilarious and does some quite rediculous and unreal things at times, but it's a good watch. The cards are nothing like yugioh however, and those accusing it of such as no different than those of us repsonsible for the decline in Digimon fan base.
WHat you do is take the top five cards from your deck and play them in front of you without looking. These are your shields. These are you're only protection from losing the game. You play cards form your hand as mana. once a card becomes mana, it loses all abilities and powers that card normaly would have. By tapping your mana, you may summon creatures and cast spells. TO summon a creature or cast a spell, you must tap a sufficient number of mana and at least one mana has to be of the same civilization as the card your trying to summon.The mana becomes untapped next turn. The civilization is determined by teh background fo the card. There or five civilaztions: Fire, Dark, Light, Nature, and Water.Each civilization specializes in particular card strengths. Water is mostly draw power and unblockable mosnters (mentioned later). Fire is raw power and double breakers(Also explained later). Nature is mana production, light is excellent defense, and darkness is evil cards that find other ways of taking you down. Monsters that are just summoned get what is called "Summoning sickness". Basically that monster can't attack the turn its summoned.
Once a monster attacks, it becomes tapped. Monsters cannot attack other monsters unless the monster being attacked is tapped. A monster can attack a tapped monster or go for teh opponent's shields. Once your opponent looses all five of his or her shields and is then attacked directly, they lose the game. "Broken" shields get sent to the hand. If the shield is what is called a "Shield-trigger" spell card, trhen when it's broken you have the choice of casting it with no mana cost. Monsters marked with double breaker break two shields when they attack instead of one.
The most common types of monsters are "Blockers" and "Power attackers" When you tapp a blocker while your opponent attacks, your blocker intercepts the attack and the two monsters battle. Like any game, teh monster with the highest attack strength wins. Power attackers gain so much extra strength while they are attacking, but return to their normal strength while they are tapped. All tapped monsters are untapped come teh next turn.
lastly but not least there are evolution creatures. These creatures evolve from creatures of teh same subspecies, which can be found under the creature name. They are summoned like normal monsters and are palced ont eh creature they are evolving from. Unlike normal creatures, these ones do not get summoning sickness and are extremely powerful. A well placed evolution creature can easily change the tide of a game.
That is basically the rules for the game. As you can see, on ly in areas is it like yugioh but it is very different. It has more in comparison to pokemon or magic than yugioh.