To unlock Xbox Live Gamerscore points, complete the following Achievements! Yay!

Achievement	How to unlock
Abridged ( 10 points )	Completed "Extending Platform" without using the rope.
Boiler Room Perfectionist ( 20 points )	Completed all of the boiler room levels.
Castle Reclaimed ( 10 points )	Defeated the guardian of the clocktower.
Clock Tower Perfectionist ( 20 points )	Completed all of the clocktower levels.
Dungeon Perfectionist ( 20 points )	Completed all of the dungeon levels.
Face The Fear ( 10 points )	Completed "Spike Dodging" without using the teleporter.
Gallery Perfectionist ( 20 points )	Completed all of the gallery levels.
Graveyard Perfectionist ( 20 points )	Completed all of the graveyard levels.
Master Of Time ( 10 points )	Completed a time travel level.
Ninja ( 10 points )	Completed "In One Way..." in less than 16 seconds.
Shmu Herder ( 10 points )	Completed a level containing Shmu.
Teamwork ( 40 points )	Completed all the CoOp levels.