Due to Goat Format's age, certain game mechanics and individual card texts and rulings differ from modern Yu-Gi-Oh. Below is a list of major changes and frequently asked questions. For a more comprehensive list, visit Format Library's page on the subject.
The following commonly played cards have each received errata in modern Yu-Gi-Oh, but use their original card texts in Goat Format:
Dark Magician of Chaos
"When this card is Normal or Special Summoned: You can target 1 Spell Card in your Graveyard; add that target to your hand. Banish any monster destroyed by battle with this card. If this face-up card would leave the field, banish it instead."
"You can send this face-up card you control to the Graveyard; Special Summon 2 Level 3 or lower Beast-Type monsters from your Deck, but destroy them during the End Phase."
"If this card is sent from the field to the Graveyard: Add 1 monster with 1500 or less ATK from your Deck to your hand."
"During your Standby Phase, if this card is in your Graveyard: You can add it to your hand."
"Pay 800 LP, then target 1 face-up monster your opponent controls; take control of that target until the End Phase."
"All "Gravekeeper's" monsters gain 500 ATK and DEF. Cards in either player's Graveyard cannot be banished. Negate any card effect that would move a card in the Graveyard, other than itself, to a different place."
Ring of Destruction
"Target 1 face-up monster on the field; destroy that target, and if you do, inflict damage to both players equal to that target's ATK."
If your Apprentice Magician controlled by your opponent is destroyed by battle, your opponent, not you, gets the effect.
This card's damage dealing effect is treated as a Trigger Effect rather than a Continuous Effect.
If a card or effect is Chained to this card's Ignition Effect to remove it from the field or flip it face-down, it resolves without an effect. This also applies to Thousand Eyes Restrict.
If this card targets a monster with it's effect but is then removed from the field before the effect resolves, the target is sent to the graveyard. This also applies to Thousand Eyes Restrict.
If this card's ability resolves after targeting a Sangan and is then either is sent to the graveyard, Sangan's ability will trigger. This also applies to Thousand Eyes Restrict.
This card functions as though it has this text: "After this card resolves, if a monster you control is sent to your Graveyard this turn: You can Special Summon 1 monster with 1500 ATK or less from your Deck."
If you banish an opponent's Fusion Monster with this card, your opponent must also banish all copies of that Fusion Monster from his or her Fusion Deck.
You must show your opponent the monster you select from your Deck for this card’s effect. If you have no eligible monsters, your opponent gets to see your Deck to verify.
The effect of "Sangan" only activates when it is sent from the field to the Graveyard, not from your hand or Deck, and not if it is removed from play.
If the Summon of this card is negated with "Horn of Heaven" or "Solemn Judgment" you do not get its effect.
If you control your opponent’s "Sangan" and it is destroyed, your opponent gets the effect since it activates in his/her Graveyard.
You can chain to "Sangan"’s effect.
If "Spirit Reaper" is targeted by the effect of "Relinquished", "Spirit Reaper" is an Equip Spell Card after the effect of "Relinquished" resolves, so it is not destroyed.
The following are clarifications on rules that have changed since the original Goat Format.
When the turn player has priority after a successful Summon, they can activate the effect of ANY Cost Effect monster on their field; you are not limited to using the effect of the monster that was just Summoned.
There is no maximum number of cards you can include in your Main and Fusion Decks (now Extra Deck). However, you must be able to shuffle your Main Deck without assistance within a reasonable time.
The player with the first turn of the game conducts a normal draw during his or her Draw Phase.
Only one Field Spell may be active at a time. If you activate a Field Spell while your opponent controls one, the old one will be destroyed. You can also destroy your own Field Spell to activate or set a Field Spell from your hand.
If a replay occurs after you declare an attack with a monster during your Battle Phase, you may opt out of attacking with that monster immediately following the replay and still have the option to attack with that same monster later in the Battle Phase.
You can activate a card or effect that adds a specific card or one that meets certain criteria from your Deck even if there isn't a card in your Deck that can be added.
(EX1) You have two copies of Thunder Dragon currently banished and the third one in your hand. You can activate the effect of Thunder Dragon, discarding it for its cost. Now that you have a LIGHT monster in your Graveyard, you can banish it and a DARK monster to Special Summon Black Luster Soldier - Envoy of the Beginning!
The quick effects of Continuous Traps can only be activated if the card has already resolved, on a separate Chain.
(EX1) Player A sets Royal Oppression and suspects his opponent, Player B, will try and activate Metamorphosis on her next turn. If Player A waits to activate Royal Oppression until Player B activates Metamorphosis, he will be unable to negate the activation and effect of Metamorphosis with Royal Oppression on the same Chain, as Royal Oppression has yet to resolve. Therefore, Player A must activate and resolve Royal Oppression earlier in Player B's turn, like during the Draw or Standby Phase. By doing this, Player A is forcing Player B to either activate Metamorphosis into the Royal Oppression (which can now negate the card with its quick effect for 800LP) or wait until either Player A doesn't have enough Life Points to activate its effect or until she draws a card that will remove it from the field.
Upon the successful Summon of a monster without a mandatory Trigger Effect, the turn player may activate the Ignition Effect of any of his or her cards at Chain Link 1 during the Summon response window using turn player priority.
(EX1) Player A Normal Summons Exiled Force and uses turn player priority to activate its Ignition Effect at Chain Link 1, Tributing itself for its cost and targeting Player B's Airknight Parshath. Still in the Summon response window, Player B activates Trap Hole at Chain Link 2. No other cards or effects are added to the Chain. Resolving the Chain: Trap Hole tries to resolve, but resolves without an effect as Exiled Force is in the Graveyard; Exiled Force's effect resolves and destroys Airknight Parshath. In this example, Player A uses turn player priority to Summon, activate and resolve the effect of Exiled Force to "dodge" the effect of Trap Hole.
(EX2) Player A Special Summons Black Luster Solder - Envoy of the Beginning and uses turn player priority to activate its Ignition Effect at Chain Link 1, targeting Player B's face-down Sinister Serpent. Still in the Summon response window, Player B activates Torrential Tribute at Chain Link 2. No other cards or effects are added to the Chain. Resolving the Chain: Torrential Tribute resolves and destroys all monsters on the field; Black Luster Soldier's effect tries to resolve, but resolves without an effect as Sinister Serpent is in the Graveyard. In this example, Player A uses turn player priority but is "blocked" by Player B's Torrential Tribute, preventing him from banishing her Serpent Serpent and taking out his Black Luster Soldier in the process.
(EX3) Player A controls a Black Luster Soldier - Envoy of the Beginning. Player B controls a face-down Cyber Jar, a face-down Chain Disappearance, and a face-down Divine Wrath. Player A Normal Summons Mystic Swordsman LV2 and uses turn player priority to activate the Ignition Effect of Black Luster Soldier at Chain Link 1, targeting Player B's Cyber Jar. Still in the Summon response window, Player B now has a choice to make! She can either activate Chain Disappearance at Chain Link 2 to banish the Mystic Swordsman LV2 OR activate Divine Wrath at Chain Link 2 to negate the activation and effect of Black Luster Soldier and destroy it, but she can't do both since a Normal Trap can't be Chained to a Counter Trap and Divine Wrath must be activated in direct response to a monster effect (at the next Chain Link). Player B opts to activate Divine Wrath at Chain Link 2, discarding Sinister Serpent for its cost. No other cards or effects are added to the Chain. Resolving the Chain: Divine Wrath resolves and negates the activation and effect of Black Luster Soldier and destroys it; Black Luster Solder's effect tries to resolve, but resolves without an effect as its effect was negated. The Summon response window has now passed and Player A is free to proceed to his Battle Phase and attack Player B's Cyber Jar, destroying the monster immediately with its effect. In this example, Player A uses turn player priority to force Player B into a situation where only one of her cards can be used, so she must choose which threat to eliminate because she can't eliminate both.
The following are clarifications on common questions that arise during Goat Format play.
Question: Can I activate Breaker the Magical Warrior's Ignition Effect with turn player priority upon Normal Summoning it?
Answer: No, Breaker has a mandatory Trigger Effect that activates when it's Normal Summoned. This effect must resolve to place a Spell Counter on Breaker. Only after this can you activate the Ignition Effect of Breaker to destroy a Spell or Trap.
Question: Can I return Sinister Serpent to my hand during my Standby Phase following the turn it was destroyed by battle with my opponent's Dark Balter the Terrible?
Answer: No, as the effect will be negated and resolve without an effect after you activate it. If it leaves the Graveyard (through Premature Burial or Call of the Haunted for example) and then re-enters, the effect will resolve properly.
Question: Can Relinquished/Thousand-Eyes Restrict activate its Ignition Effect targeting a token?
Answer: Yes, it can equip a token as an Equip Card. In that case, its ATK and DEF become equal to the original ATK and DEF granted to the token by the card effect that created it.
Question: Can I use Premature Burial or Call of the Haunted to Special Summon a Thousand-Eyes Restrict that was Special Summoned with the effect of Metamorphosis?
Answer: No, as it was not properly Fusion Summoned.
Question: Can I activate Delinquent Duo if my opponent only has 1 card in hand?
Question: What happens if I gain control of my opponent's monster with Snatch Steal and the equipped monster is later flipped face-down?
Answer: The monster remains on the current side of the field and Snatch Steal is sent to the Graveyard.