Depending on what you did during the game will determine on which of the four slightly different endings you get. Below is a list of the tasks that need to be completed for each of the four endings to the game.

Unlock Ending A:

In Chapter 8 rescue Leanna from the Spider Pit.

In Chapter 9 purge Xana.

Take the Skull of Shadows and place it on the altar


Unlock Ending B:

In Chapter 8 rescue Leanna from the Spider Pit.

In Chapter 9 purge Xana.

Take the Skull of Shadows and throw it down the pit to your father.


Unlock Ending C:

In Chapter 8 don't rescue Leanna from the Spider Pit or kill her.

Take the Skull of Shadows and place it on the altar


Unlock Ending D:

In Chapter 8 don't rescue Leanna from the Spider Pit or kill her.

Take the Skull of Shadows and throw it down the pit to your father.

At the console enter 'give' followed by a space and then the following codes to unlock the corresponding items.

Unlock Bow:
Weapon_arxcrossbow

Unlock Rope Bow:
Weapon_arxcrossbowrope

Unlock Long Bow:
Weapon_mm_bow_long

Unlock Club:
Weapon_arxclub

Unlock Daggers:
Weapon_arxdaggers

Unlock Long Sword:
Weapon_arx_long_sword

Unlock Short Sword:
Weapon_arx_short_sword

Unlock Sword of the Dragonclaw:
Weapon_arx_silver_sword

Unlock Full Health Potion:
Item_potion_full_life

Unlock Stone Skin Potion:
Item_potion_stone

Unlock Antidote:
Item_potion_cure_poison

Unlock Health Potion:
Item_potion_life

Unlock Mana Potion:
Item_potion_mana

Unlock Orc Shield:
Weapon_mm_shield_orc

Unlock Death Knight Shield:
Weapon_mm_shield_deathknight

Unlock Cheat Mode
To unlock the following cheats you must first enable the developer's console under the 'Key Settings' section of the 'Advanced Settings' menu during gameplay by entering 'sv_cheats 1' without the quotes into the console.

Unlock God Mode:
God

Unlock Infinite Arrows:
Arrows_unlimited 1

Spawn an Item:
Give (item)

No Clipping:
Noclip