To unlock the limitation option, get 100% completion by collecting every single card in the game. Now you can choose to have restricted cards to be no longer restricted.
2/10/2004
View the staff credits again.
To do this, you must have already viewed the staff credits at least once. To view the credits again, input the old famous Konami code by pressing Up, Up, Down, Down, Left, Right, Left, Right, B, A at the selection menu.
2/11/2004
Unlock Boosters
To unlock these boosters, you must have ten wins against the specified duelist.
Beat all five Ghouls ten times each. You must use a deck without any magic or trap cards to duel Ishizu.
Bonz
Beat all tier 1 duelists 3 times each. Open at least five Barrel Dragon booster packs.
Mako Tsunami
Beat all tier 1 duelists 3 times each. Open at least five Black Luster Soldier booster packs.
Weevil Underwood
Beat all tier 1 duelists 3 times each. Open at least five Black Skull Dragon booster packs.
Rex Raptor
Beat all tier 1 duelists 3 times each. Open at least five Blue Eyes White Dragon booster packs.
Espa Roba
Beat all tier 1 duelists 3 times each. Open at least five Red Eyes Black Dragon booster packs.
Mai Valentine
Beat all tier 2 duelists 5 times each. Have a Harpie Lady card in your trunk, and no Harpie's Feather Duster card in your deck.
Maximillion Pegasus
Beat all tier 2 duelists 5 times each. Have at least one of: Toon World, Blue-eyes Toon Dragon, and Toon Summoned Skull cards in your trunk.
Bandit Keith
Beat all tier 2 duelists 5 times each. Have a Barrel Dragon card in your trunk and none in your deck
Joey Wheeler
Beat all tier 2 duelists 5 times each. Have a Jinzo card in your trunk and none in your deck.
Yami Bakura
Beat all tier 5 duelists 15 times each. Duel Bakura three times in a row, and on the fourth time, Yami Bakura will appear and be unlocked.
Simon
Beat all tier 5 duelists 15 times each. Duel either Tea, Tristan, or Truesdale three times in a row and on the fourth time, Simon will be unlocked.
Yami Marik
Beat all tier 5 duelists 15 times each. Duel Marik three times in a row, and on the fourth time, Yami Marik will appear and be unlocked.
Duel Computer
Beat all tier 5 duelists 15 times each. Duel Seto Kaiba three times in a row, and on the fourth time, the duel computer will be unlocked.
Yami Yugi
Beat all tier 5 duelists 15 times each. Duel Yugi three times in a row, and on the fourth time, Yami Yugi will appear and be unlocked.
Seto Kaiba
Beat Bakura, Mai, Joey, Ishizu, and every Ghoul ten times each.
Shadi
Beat Bakura, Yugi, Mai, Joey, and every tier 4 and tier 5 duelist 10 times each.
Ghouls (random)
Beat Bandit Keith, Joey Wheeler, Mai Valentine, and Pegasus seven times each.
Marik Ishtar
Beat each of the five Ghouls once.
Ghouls (selectable)
Beat Marik Ishtar once.
2/15/2004
Permanently Unlock Duelists
Certain duelists have extra requirements to unlock. You must constantly meet these requirements, or they will vanish from the selection screen. If you defeat a duelist with special requirements ten times, they will be permanently selectable, regardless of their past requirements. For example, if you beat Joey ten times, you can then duel him even if you have a Jinzo card in your deck. Losses and ties don't count against your total wins.
2/23/2004
Keep Thunder Nyan Nyan on the field
Thunder Nyan Nyan is a powerful 1900 ATK Light element monster that is immediately destroyed if you have a non-Light element monster face-up on your side of the field. However, if you use Snatch Steal to take a monster from your opponent, it doesn't count as a monster on your side of the field, and therefore Nyan lives. This doesn't work with Change of Heart.
2/24/2004
Spirit Reaper Glitch
Spirit Reaper's effect states that it cannot be destroyed as a result of battle, making it a perfect shield, but if it is targeted by a magic, trap, or monster effect card, then it is destroyed immediately (this includes equip magic cards such as United We Stand or Axe of Despair). However, if you use an equip card on Spirit Reaper, the equip magic card will be destroyed, but Spirit Reaper will remain on the field.
3/8/2004
Dark Ruler Ha Des Glitch
If you attack and destroy a Slate Warrior with a Fiend type monster on your side of the field when you have a Dark Ruler Ha Des face up on your side of the field, the slate warrior will still weaken your monster, even though the effect of Dark Ruler Ha Des should prevent that from happening.
3/9/2004
Fiber Jar + Solemn Wishes gitch
Have Solemn Wishes active on your side of the field and then filp summon Fiber Jar activating its ability, when you go to draw your cards although Solemn Wishes isn't on the field you still gain 2500 life points!
Beat every duelist 20 times, then at the title screen press L, R, Select, A, B, Left, Right, Up, Down, Start
12/15/2004
Graverobber Card Exploit
The Graverobber card states that you can take a spell card from your opponent's graveyard and it will only work if you activate the spell card you took during your turn, but you have to pay 2000 life points to activate it.You can play the card you took without paying the 2000 life points by first placing it on the field and then activating it while its on the field. The game somehow forgets the card is in play because of Graverobber and normally plays out the card. You will however end up paying the 2000 life points if you play the card you took while its in your hand, so make sure you place the spell card on the field first before you play it so to avoid the 2000 life point penalty