To unlock the following complete the corresponding tasks

Unlock Valkyrie Master:
Using default settings with the Valkyrie get 1st place on the in-game score board

Unlock Warrior Master:
Using default settings with the Warrior get 1st place on the in-game score board

Unlock Wizard Master:
Using default settings with the Wizard get 1st place on the in-game score board

Unlock Elf Master:
Using default settings the with Elf get 1st place on the in-game score board

Unlock Co-Op:
With another player using default settings complete Level 10 on Xbox Live

Unlock Co-Op Master:
With another player using default settings finish Level 20 on Xbox Live

Unlock Game Master:
Using default settings complete Level 100 (credits can be used)

Unlock Max Co-Op:
With 3 other people start an online game of Gauntlet

Unlock Bling:
Using default settings collect 10 Treasure Chests on Xbox Live

Unlock High Score:
Using default settings acquire an Xbox Live Co-Op score of 100,000

Unlock Treasure:
Collect 11 treasures and exit during a treasure level

Unlock Anti-Theif:
Kill a thief