Achievements...
	Different ending...
	Walk through walls in Marble Z...

Complete the following achievements to unlock Xbox Live Gamerscore points.

Achievement	How to unlock
Centurion ( 10 points )	Get 100 or more rings.
Chaos Emerald ( 10 points )	Get one Chaos Emerald.
Chaos Master ( 35 points )	Get all the Chaos Emeralds.
Clear Green ( 5 points )	Clear the Green Hill Zone.
Fast Green ( 10 points )	Beat Green Hill Zone Act 1 in under 35 seconds.
Fast Marble ( 15 points )	Beat Marble Zone Act 1 in under 80 seconds.
Spring Yard Zone ( 7 points )	Get to the Spring Yard Zone.
Star Light Zone ( 5 points )	Get to the Star Light Zone.
Fast Win ( 30 points )	Beat the game in under 40 minutes.
Labyrinth Zone ( 8 points )	Get to the Labyrinth Zone.
Perfect Win ( 40 points )	Beat the game without dying.
Win ( 25 points )	Beat the game.

Beat game with all chaos emeralds.

When you ride the green block accross a sea of lave, there are a couple of big blocks in front of you with rings on. If you hold the D-PAD DOWN button, Sonic will crouch. The green block will go underneath the blocks, but sonic will remain on it, and pass through the walls. This only works while crouching.