Hold L1 + R1 + Triangle + Square + Circle + X and press Start during game play. This will unlock options for 'Invulnerability' and 'Level Warp'. After using the 'Level Warp' option, press Circle to resume the game.
Defeating Green Slimes
When battling the Green Slimes in the Sewers, use weapons that have large damage attacks, such as swords and maces. When attacking the slimes, hang around the edge of a corner and let them come to you. Then, ambush them when they are close enough to your character. This is the best way to battle in the Sewers, and it saves your health potions.
Defeating Luvia's beasts
When fighting in Luvia's Laboratory and you get to the end where she sends two beasts to attack you, only go forward slightly. One of the beasts will chase you. Stay in the bottom portion of the room and use the crossbow on it. This is easier with two players. Eventually it will die and then you can defeat the second one in any way desired.
Defeating the Harnak
To defeating the Wayfare Inn Boss, make sure you have a ranged weapon. First, take out the underlings. Do not hit the Boss; he will not attack you until you attack him. Once all the Goblin underlings are dead, you can attack Harnak. When he starts to chase you, run towards the tables on the right. Jump to get over them. Once on the top side of the tables, line up on the corner closest to the fireplace. This should get Harnak stuck by the bottom table, leaving you free to hit him with your ranged weapon.
Duplicating Items
Get next to a save point. Save your game. Drop the items you wish to duplicate. Reload your character. Pick up the dropped items. Repeat this as may times as desired. You will have the number of items you had when you saved plus the ones that you picked up after reloading.
Easy experience
This trick works with all characters who are able to buy experience from their NPC associate, such as the cleric and the church of Helm and necromancer with the Oglulkluer person. Make a lot of gold (use the duplicate item trick if desired). Save the game. If you already used up your NPC experience you will need to start a new game. However, if you have not, save. Spend all your money on experience. Save a new saved game. Load your old saved game before you spent your money on experience. Load your character from the saved game after you spent the money. Spend more money on experience and repeat as many times as desired. Along with the item duplication trick, you can make your character as powerful as desired. Before you have spoken to the person who gives you experience for talking to them (for example, when playing as Ysuran it is Omduil), duplicate items to get a lot of gold. Then, save your game in two slots. Speak to him as many times as you can to gain experience, then save on one of the slots. Exit to the menu, then load the duplicated original from before you bought the experience. With that loaded, import your character from the newer file. You will have the experience, but you can buy it all over again. Always save to the newer file, load the older game, then import the newer character.
Easy gold and experience
In some situations, your character may be awarded a prize of 1,000 gold and 1,000 experience points. However, before you claim a prize, save the game and get your award. Load a previously saved game before you get your gold and experience points. Then, load the character that already has the gold and experience points. Keep repeating this processes to get a lot of gold and experience points.
Easy way to get Artemis
Start a new game on extreme difficulty. Then, hold L1, R1, circle, X, triangle, and square, now press start while holding them. This will bring up a screen with resume game, level warp, and invulnerability. Select level warp and go to BGATE3. This will have you go to Baldurs Gate after you defeat Mordoc and Randalla is thanking you. When the credits are over you will have Artemis.
Extreme Mode
To unlock Extreme Mode, beat the game once. Extreme Mode requires a saved character to play.
Increase rank
Each character has their own person to talk to (except Dorn). Most of the time, these contacts ask for money. When you get a chance, pay them the amount of money they ask for. In Act 3, the character's contact will ask them to do one final mission. Do so and your character will earn a new rank that makes them even more powerful. Dorn also gets this, but not until Act 3.
Level 10 Character
Hold L1 + R1 + Triangle + Square + Circle + X and press L2 during game play. Your current character will now be at level 10, with 45 feat points and 500,000 gold.
Play as Drizzt and Artemis
To unlock Drizzt, beat the game on any difficulty. To unlock Artemis the Human, complete the game on Extreme Difficulty and start a new game. Move the cursor to Alessia Faithhammer and then press DOWN once for Drizzt and DOWN, DOWN for Artemis.
Start extreme mode with better items
Unlock extreme mode, then start a new game in any other mode (for example, easy) with Drizzt for player one. Give him as many weapons, armor, etc. that he can carry then save the game. Then, select extreme mode and choose anyone. Bring him into the game as player one. He will have all the weapons that were given him or her.