Cheats:
Secret dungeon:
Send seven mails to another player through Mog Net. Then send four mails using
Mog Net to the NPC "The 4 Old Men", and another four mails to "King Alus". It
does not matter what order this is done, as long as Alus is last. After reading
the fourth one you will unlock the new dungeon. Ride on the Nautulus and go east
of the floating continent. Once there you will see a shadow in the water.
Go underwater here and move into the coral to enter a cave. There is no real
dungeon here, but there is a difficult boss, Iron Giant.
Onion Knight job:
Register someone multiple communication IDs on Mog Net. Send seven messages to
another player. Send and receive four messages from Topapa. After reading the
fourth one you will get a message giving your a mini-quest. Go to Uoul and talk
to Topapa. Go to the cave that is to the north of the other cave. Enter, then
defeat the three Bombs to get a piece of crystal. This will unlock the Onion
Knight as a job.
Easy Gil:
Go to the Town Of The Ancients and talk to the child two stories up the grass
hills. He is back behind the stairs. He will tell you that he will give you a
prize if you ride around the continent. Leave town and go east a bit. Get a
Chocobo and ride around the outside of the continent. Go back and talk to the
child for your rewards. Sell them, then repeat.
Spells replaced by items:
You can use certain items instead of spells if you run out of MP. For example,
if your Black Mage wants to use Fire but is out of MP, go to the item screen
and use the item Fire Staff. This seems to only work if your character is able
to equip the item that is being used. Also, not all items work. Items that work
include the Ice Staff, Fire Staff, Light Staff, and Salamd Sword.
Shurikens:
If you are not near the end of the game and you keep finding shurikens but cannot use them, do not worry about it. You will be able to use them later when you unlock the Ninja job.
Level 8 spells:
You will not be able to use level 8 spells until you level up classes of Devout
(White Magic; better form of White Mage) and Magus (Black Magic, better form of
Black Mage). Level 8 Black Magic is Flare, Death, and Meteor. Level 8 White Magic is Tornado, Arise, and Holy.
Legendary items:
The legendary items of Eureka are mainly used by Knight, Ninja, Devout, and Magus. Knights get two legendary items, Excalibur and Ragnarok, equaling a total of 277 attack. Ninjas get the legendary dark sword Masamune. It has 132 attack by itself. White Mages can use, but Devouts use the legendary item Elder Staff. It casts Cura. Black Mages and Magus use Omnirod. It does not cast anything, but when used in melee it inflicts gradual petrification.
Fast and safe job leveling:
Reach at least level 20 and have decent armor. The best place to level up your
job is around Ur, dealing with the weakest enemies in the game, Goblins. Have a
Bard with a Dream Harp so you do not waste potions or MP. You can reach job level 99 in 98 battles by guarding against this enemy, only receiving 1 point of damage from each attack. During each battle, there is a certain number of times according to the number of actions required to level up a job. For example, a Bard requires 5 actions job level 1 to 14, and 6 actions job level 15 and up. The need to heal is unnecessary, but if desired you can use the Bard's Sing ability every ten battles to remain at maximum HP.
Achievements:
Achievement - How to unlock
Collecting is Half the Battle - Complete 50% of the Bestiary.
Filling Up the Grotesquerie - Complete the entire Bestiary.
For a Rainy Day - Save up 50,000 gil.
Glutton for Arms - Obtain every weapon in Eureka, the Forbidden Land.
Gone Adventuring with the Wind - Defeat Djinn and obtain the Wind Crystal.
I, My, Me, Mine - Open every treasure chest.
Jack of All Trades - Attain level 99 with all jobs for all characters.
My Little Esper - Obtain a summonable creature.
No Such Thing as Too Many - Obtain all the summonable creatures.
Nose for Treasure - Open 50% of all treasure chests.
One Sword to Slay Them All - Obtain the Ultima Weapon from the Legendary Smith.
Quelling the Tremors - Defeat Titan and obtain the Earth Crystal.
Release the Kraken - Defeat Kraken and obtain the Water Crystal.
Some Like It Hot - Defeat Salamander and obtain the Fire Crystal.
Steely Resolve - Defeat Iron Giant.
Warriors of Light - Defeat the Cloud of Darkness.
When I Grow Up I Want to Be... - Attain level 99 with any job.
Who Wants to Be a Gillionaire? - Save up 500,000 gil.