Successfully complete the indicated task to unlock the corresponding treasure:

Challenge Of Hades: Successfully complete the game on any difficulty.
Character Concept Art: Successfully complete the game on any difficulty.
Environments Concept Art: Successfully complete the Challenge Of Hades.
God Mode: Successfully complete the game on any difficulty.
In-Game Movies: Successfully complete the game on any difficulty.
Inside Ready at Dawn Studios: Successfully complete the game on any difficulty.
Making Of Attica: Successfully complete the game on the God difficulty.
McKratos costume: Successfully complete the Challenge Of Hades. This costume increases your Attack skill.
Mime Of War costume: Successfully complete the game on the God difficulty. This costume gives 10x Red Orbs and makes weapons invisible.
Outtakes Concept Art: Successfully complete the game on the God difficulty.
Spud Of War costume: Successfully complete the game on any difficulty. This costume increases your Magic skill.
The Lost Levels: Successfully complete the Challenge Of Hades.