Accomplish the indicated achievement to get the corresponding number of 
Gamerscore points:

Achievement                   How to Unlock
--------------------------------------------------------------
Animal Handler (20)         - Collect all of the animals
Arena Master (15)           - Win 40 ranked arena matches
Conscientious Objector (20) - Complete the barbarian area without attacking once
Deer Trainer (20)           - Navigate the abandoned mill without hitting any obstacle
Glork (15)                  - Win 20 ranked All You Can Quaff Matches
K.I.S.S (15)                - Collect all four princess' kisses in a multiplayer game
Maximum Firepower (10)      - Using a catapult, fling a knight with maximum power
Medic! (10)                 - Resuscitate all of your fallen comrades
Melee is Best (15)          - Defeat any boss without using any magic
The Traitor (20)            - Defeat any boss by playing one of his own minions
Traditional (20)            - Complete the game using any character
Treasure Hunter (20)        - Find and dig up ten buried items