Feed your little Grunty: 4 Cordycep, 1 Mandragora, 2 Piney Apple, 1 Snaky Cactus, and many Golden Eggs until it is an adult.
Completion bonus
Successfully complete the game to unlock the parody mode. Parody mode replaces the original text with joke dialogue. Note: This is only available in the Japanese version.
Defeat Cubia
In order to beast him easily, all you have to do is bring Mistral and Piros (Mistral is required anyways). Make sure you're at least at level 36. Now you don't attack Cubia head-on, you have to destroy the core. The core sends out miniature cores, and they heal, attack, and stuff like that. Destroy all the 'Repth' cubias, and then all the attacking ones. MAKE SURE YOU ONLY HAVE ONE LEFT. Next, you just beat the snot out of the core until it dies! But be warned: Do not have your Partner(s) attack the core- have Mistral heal, and your other choice(preferably Piros) Attack it until it dies.
Defeating Martina R
When fighting Martina R use a scrool called the Moon on her to put her to sleep. Then use a item called Beast Bane on her (Found in trade with a non-playable character named Koji) to eliminate her magical defenses. Now you can inflict magical damage against her. Use the summoning scrools against her to kill her in two hits.
Drain Arc
After obtaining the last Ryu Book (Ryu Book VIII), Data Drain a few more times to obtain Drain Arc, which allows you to Data Drain multiple enemies at one time.
DVD secrets
The DVD that is included with the game has a secret section. It reveals secrets in the game. Highlight the gallery of pictures, then press Right. The pointer will disappear. Press X or Enter, then scroll right and left between secrets one to ten.
Extra health sp and key items
After beating the game, go back to the first root town and visit Haunted "Forbidden Holy Ground" four times. Each time you see a special cut scene from the show .Hack//Sign. You also get a special key item and a golden or silver grunty that will increase you health and magic strength.
Getting good weapons
Visit your Grunty to get good weapons that might help. Just go to Lamda or the first place where you raised your own Grunty then talk and trade.
Grunties
In most root towns you will find a baby grunty, if you feed these babies lots of foods you can aqquire in the field it will become an adult and give you the grunty flute, if you use it on the field it will come to help. This will only work if you are in the same server as that grunty.
High level fields
In the Lambda server, if you type in Chosen, Hopeless, (and another keyword) you will get fields that range from level 48 to 50.
Key Axe
If you completed .hack Part 1: Infection and finished the OVA Keyword dungeons you should have an Ice Bar. If not, go to Delta: Hideous, Organ Market, Scaffold, and when you reach the Statue of Gott you will receive the Ice Bar. Go to the Root Town and look for a player named Panta. You trade the Ice Bar to him for a Level 38 Key Axe.
OVA Keyword
In the OVA that comes with the game, there is a hidden Keyword shown while Mai is on the computer: Lambda: Capricious, Unending, Corridor. When you reach the statue of Gott at the end of the dungeon, you will get Chinese Food. Go back to the Root Town and look for a player named Annri. You can trade the Chinese Food for a Super Wufei (a very powerful spear for either Nuke Usagimaru or Gardenia).
Rare weapons
If you Data Drain monsters, you can either get Virus Cores or weapons/armor. Most high level monsters have very rare weapons and strong armor. Most of these monsters are above level 45; be careful when fighting them. If you do not receive the item, keep Data Draining that monster. However, do not Data Drain too much where you are in danger of system crashing:
House Golem: Laevateinn (Heavy Blade)
Wander Demon: Rod of Pattern (Wave Master)
Mad Witch: SWORD (Blademaster)
Harpy Queen: Great Elite (Wavemaster), Jishuwen (Long Arm)
Easter Rock: 8 Key Guardian (Heavy Axeman)
Squidpod: Fishskin (Twin Blade)
King Worm: Bureido (Blademaster)
Angolmere: Crimson Raid (Twin Blade)
Secret Characters
There are three other secret characters to unlock. Here are their names and how to get their addresses.
Moonstone: You will see him in some of the Lambda server areas. Later, you will get an e-mail from him. You will go to Lambda: Bottomless, Guwaffing, Raw Ore with Moonstone (auto) and someone else. It would be prefered to take a Wavemaster along.
Nuke Usagimaru: Read the board after completing Delta: Soaring, Sky Bounded, Abyss. You must go to Lambda: Lightless, Distant, Dead Lands alone. I suggest training before you go.
Rachel: Read the board after completing Delta: Soaring, Sky Bounded, Abyss. You must go to Lambda: Collapsed, Pagen, Remains with a random party of three.
Snakey Grunty (Lambda Server)
Feed your little Grunty 2 Cordycep, 2 La Pumpkin, 2 Mandragora, 2 Twilight Onion, and 16 Golden Eggs.