Collect 25% of the prize bubbles on the story levels

Kill Zeus

Collect all of the Minotaur Horns

Collect all of the Gorgon Eyes

Collect all of the Phoenix Feathers

Solve Hera's Gardens

Open the Gates of Tisiphone

Kill the Poseidon Princess

Kill Hermes and acquire his Boots

Cover Kratos in 500 buckets of blood by killing the enemies

Kill Hades

Upgrade any weapon to the next level

Kill Poseidon