Accomplish the indicated task to get Gamerscore points:

Anti-Thief:
Kill a thief.

Bling:
Collect 10 treasure chests on Xbox Live on the default settings.

Co-Op:
Successfully complete level 10 on Xbox Live with another player on the default settings.

Co-Op Master:
Successfully complete level 20 on Xbox Live with another player on the default settings.

Elf Master:
Reach first place on the game score board with the Elf on the default settings.

Game Master:
Successfully complete level 100 on the default settings.

High Score:
Score 100,000 points in an Xbox Live Co-Op game on the default settings.

Max Co-Op:
Start a four player Xbox Live Co-Op game.

Treasure:
Get 11 treasures and complete a treasure level.

Valkyrie Master:
Reach first place on the game score board with the Valkyrie on the default settings.

Warrior Master:
Reach first place on the game score board with the Warrior on the default settings.

Wizard Master:
Reach first place on the game score board with the Wizard on the default settings.

Press Y to add 700 health.

If you are stuck or bored on a level, have all characters remain completely idle. After approximately two minutes, all the walls will turn into exits.