Rules/Game Mechanics

If you play current format Yu-Gi-Oh!, learning the rules of Goat Format will not be difficult. Believe it or not, the vast majority of Yu-Gi-Oh!'s rules have not changed at all over the years. The differences that do exist are in many cases quite subtle. They are listed below. It's important to note here that if a rule is not explicitly listed here is being different in goat format, you can assume that it works the exact same way as it does in the current format. For specific card rulings, see our Individual Rulings page.
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Goat Format Rule #1: Start With 6

​Unlike in current Yu-Gi-Oh!, the player who goes first will draw a card at the start of their first draw phase. This means that they will initially have 6 cards in their starting hand.
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Goat Format Rule #2: Unlimited Fusion Deck

​Before synchros were introduced to the game, the extra deck was called the fusion deck, and it could contain as many cards as you wanted! For online dueling simulators that restrict you to only 15 cards, use the following convention: Add the 15 fusions that you think you will be most likely to use, and then if you happen to need one that you didn't add, simply use a different fusion as a proxy.

Example: You activate Snatch Steal on your opponent's Fusilier Dragon, the Dual-Mode Beast, and use Metamorphosis on it, with the intention of summoning a King Dragun. But you did not put King Dragun in your 15-card fusion deck. You inform your opponent of this fact, special summon a Darkfire Dragon from your fusion deck instead, and say, "This Darkfire Dragon will represent a King Dragun." You then send your opponent a link to King Dragun's text so that they know what it does.
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Goat Format Rule #3: One Field Spell to Rule Them All

It is not possible for both players to control a face-up active field spell. If the activation of a field spell resolves while the opponent controls a face-up field spell, the previous field spell is destroyed. It's worth noting that (in both goat format and current format) field spells must be face-up to resolve.

Example 1: Player A controls a face-up Necrovalley. Player B activates A Legendary Ocean. Player A has no response, and Necrovalley is destroyed.
Example 2: Player A control a face-up Necrovalley. Player B sets A Legendary Ocean face-down. Player A's Necrovalley will remain face-up on the field.
Example 3: Player A controls a face-up Necrovalley. Player B activates A Legendary Ocean. Player A chains Mystical Space Typhoon, targeting A Legendary Ocean. Player B has no response. A Legendary Ocean was destroyed, so it does not resolve, and Necrovalley will remain face-up on the field.
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Goat Format Rule #4: Priority for Ignition Effects

Priority is often misunderstood by newer Goat Format players, but it's actually not very complicated. The current format rules on what Konami calls "fast effect timing" and "open and closed gamestates" are found by clicking here. This is the same mechanic as what people in 2005 called "priority." Believe it or not, with one exception, everything that you will find on Konami's chart is the same in Goat Format.

In current format Yu-Gi-Oh!, when a chain or summon has finished resolving, the turn player can activate a "fast effect" (spell speed 2 or higher) before the opponent can. In Goat Format, when a chain or summon has finished resolving, the turn player can activate a "fast effect" or a monster's ignition effect before the opponent is allowed to respond. This change does not affect how trigger effects work.

Example 1: Player A summons Tribe-Infecting Virus. Player A can activate the effect of Tribe-Infecting Virus before player B can activate Book of Moon.
Example 2: Player A controls a face-up Cannon Soldier and summons Sangan. Player A can activate the effect of Cannon Soldier, tributing Sangan, before player B can activate Torrential Tribute.
Example 3: Player A summons Breaker the Magical Warrior, and its trigger effect to add a spell counter is activated. Player B may chain Ring of Destruction to destroy Breaker the Magical and deal 1600 damage before player A can use Breaker the Magical Warrior to destroy a spell/trap card. However, if he has no response to Breaker the Magical Warrior's trigger effect, then the chain will resolve, and player A can activate an ignition effect (such as Breaker the Magical Warrior's ignition effect to destroy a spell/trap card) before player B can activate his Ring of Destruction.
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Goat Format Rule #5: Replaying Attacks

In Yu-Gi-Oh!, a replay occurs when the number of the opponent's monsters changes during the battle step of the turn player. The attacking monster may then decide to attack the same monster, a different monster, or not attack at all. In current format Yu-Gi-Oh!, this replay mechanic is considered to be a "redirection" of the same attack, whereas in Goat Format, play rewinds back to the beginning of the damage step where the attack may be re-declared. This means that if the attacking player decides not to attack at all with the monster involved in the replay, it may attack again later in the battle phase.

Example 1: Player A controls an Airknight Parshath and a D.D. Warrior Lady. He declares a direct attack with Airknight Parshath, and player B activates Call of the Haunted, special summoning Dark Magician. A replay occurs, and player A attacks Dark Magician with D.D. Warrior Lady, using its effect. Then Airknight Parshath attacks directly.
Example 2: Player A attacks directly with D.D. Warrior Lady. Player B activates Call of the Haunted, special summoning Sangan. A replay occurs, and player A has D.D. Warrior Lady attack Sangan. Player B activates Sakuretsu Armor to destroy D.D. Warrior Lady.
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Goat Format Rule #6: Continuous Traps with Ignition-Like Effects

​Unlike in current format Yu-Gi-Oh!, continuous traps with ignition-like effects cannot be flipped faceup and use their ignition-like effects at the same time. They must be flipped face-up "preemptively" so to speak. This is best demonstrated by example.

Example 1: Player A activates Scapegoat while player B controls a facedown Royal Oppression. If player B activates his set Royal Oppression as a chain to Scapegoat, he would not be able to also negate the activation of Scapegoat with Royal Oppression's ignition-like effect. Royal Oppression must already be faceup before Scapegoat is activated in order for Royal Oppression's ignition-like effect to be used.
Example 2: Player A tribute summons Mobius the Frost Monarch and uses its effect to target player B's face-down Skull Lair. Player B could activate his set Skull Lair as a chain to Mobius the Frost Monarch's effect, but he could not use Skull Lair's ignition-like effect to destroy Mobius the Frost Monarch at the same time. Skull Lair must have already been face-up before Mobius the Frost Monarch was summoned in order for its ignition-like effect to be chained to Mobius the Frost Monarch's effect.
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Goat Format Rule #7: Verifying Hands and Decks

Effects that require hands or decks to be revealed in order to ensure that they have resolved correctly must always be carried out, even if knowledge of the games rules or forbidden/limited list already provide you with enough information to verify that they have resolved correctly.

Example 1: Player A activates Mind Crush, naming D.D. Warrior Lady. Player B discards D.D. Warrior Lady from his hand. Even though D.D. Warrior Lady is limited to 1, player B must still reveal his hand to verify that Mind Crush has resolved correctly.
Example 2: Nobleman of Extermination is activated and banishes Sakuretsu Armor. Both players banish a total of 3 copies of Sakuretsu Armor from their deck. They still must reveal their decks to each other to verify that Nobleman of Extermination has resolved correctly.

However, it's worth noting that tournament policy at the time stated that the purpose of checking decks was not to memorize the entire contents of the opponent's deck and was to be conducted in a quick fashion to not interrupt the flow of the game. When playing Goat Format online, players are able to screenshot each other's decks in order to gain perfect information without anyone knowing, violating the spirit of the rule regarding deck verification. Because of this, when playing online, it has become standard conduct to not verify each other's decks for cards such as Nobleman of Crossout and Nobleman of Extermination. Instead, to ensure that these cards have resolved correctly, players can send each other replays after the match.
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Goat Format Rule #8: Failure to Find

​Cards that search the deck can be used without any legal options. The one weird exception to this rule is The Agent of Creation - Venus, whose effect still requires Mystical Shine Balls in the deck to be used.

Example 1: Player A discards Thunder Dragon to search his deck for more copies of Thunder Dragon, even though he knows that he has none. The deck is still shuffled afterwards.
Example 2: Player A activates Reinforcement of the Army and finds that his deck contains no warrior monsters. The deck is shuffled, and Reinforcement of the Army is placed in the graveyard.
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Goat Format Rule #9: One Chain Per Damage Sub-Step

​In current Yu-Gi-Oh!, an unlimited number of chains can be activated during the damage step, in the "before damage calculation" window. In goat format, only one chain can be formed during this time. This comes up incredibly rarely, as there are only few viable cards in goat format that can be activated in the damage step in the first place.

Example: Player A has his X-Head Cannon attack player B's Airknight Parshath. In the damage step, player A activates Limiter Removal. Player B chains Solemn Judgment. The chain resolves, and X-Head Cannon will be destroyed in battle before player A has the opportunity to activate another Limiter Removal.
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Goat Format Rule #10: Game & Match Draws

This can be a confusing topic for some people, because the rulebook that was distributed at the time during Goat Format actually contained incorrect information about draws that was not applied in tournaments that were ran during this time.

Although the rulebook stated that a match could end in a draw (e.g. 1 win + 1 loss + 1 draw = 1 match draw), this was not applied at tournaments, as it was literally impossible to enter a match draw into the tournament software. Matches must always be played until one player has won 2 duels.

In addition, when a duel ended in a draw, the player who decided whether or not to go first during the last game got to choose again. This is in contrast to the current format, where this would instead be decided randomly.
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Goat Format Rule #11: Trigger Recognition

In Goat Format, triggers can be recognized as being met in the middle of a chain, whereas in current format Yu-Gi-Oh! this is generally not the case. Tricks involving moving monsters to a different location to prevent them from triggering will not work in Goat Format. However, like in current Yu-Gi-Oh!, trigger effects cannot be met while the monster is in the deck.

Example 1: Player A activates Compulsory Evacuation Device, targeting Player B's set Magician of Faith. Player B chains Desert Sunlight. Desert Sunlight resolves, reveals the Magician of Faith, which the gamestate now recognizes as being triggered. Compulsory Evacuation Devices returns the Magician of Faith to Player B's hand. A new chain is formed with Magician of Faith's effect as chain link 1.
Example 2: Player A activates Phoenix Wing Wind Blast, targeting Player B's set Magician of Faith. Player B chains Desert Sunlight. Desert Sunlight resolves, reveals the Magician of Faith, which the gamestate now recognizes as being triggered. Phoenix Wing Wind Blast returns the Magician of Faith to the top of Player B's deck. Magician of Faith's effect is not activated, because monster effects cannot be activated in the deck.
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Goat Format Rule #12: Monsters Equipping Monsters

In the goat format, if a monster like Relinquished or Thousand-Eyes Restrict tries to equip an opponent's monster to itself, and an effect is chained that causes Relinquished/Thousand-Eyes Restrict to be removed from the field or flipped facedown, the opponent keeps their monster (it is not sent to the graveyard). On the contrary, in current format Yu-Gi-Oh!, the monster would in fact be sent to the graveyard.

Example 1: Player A activates the effect of Thousand-Eyes Restrict, targeting Player B's Dark Magician. Player B chains Book of Moon, targeting Thousand-Eyes Restrict. Book of Moon resolves, flipping Thousand-Eyes Restrict facedown. Then Thousand-Eyes Restrict resolves without effect, and Player B keeps their Dark Magician.
Example 2: Player A activates the effect of Relinquished, targeting Player B's set monster. Player B chains Raigeki Break, targeting Relinquished. Raigeki Break resolves, destroying Relinquished. Then Relinquished resolves without effect, and Player B keeps their set monster.