Complete the following achievements to unlock Xbox Live Gamerscore points.

Achievement	How to unlock
Early Days! ( 10 points )	Win a point in a multiplayer battle.
Elite Champion ( 15 points )	Earn at least Bronze in all the Elite Challenges.
First Steps ( 10 points )	Beat a Supersonic ghost.
Grease Monkey ( 20 points )	Unlock all the car upgrades.
I am the best! ( 15 points )	Win a multiplayer battle.
No one can beat me! ( 20 points )	Win 10 multi-player battles.
Silver Arrow ( 20 points )	Earn at least Silver on all Challenges.
Skill Chief ( 15 points )	Earn at least Bronze in all the Skill Challenges.
Speed King ( 15 points )	Earn at least Bronze in all the Speed Challenges.
Supreme Being ( 25 points )	Earn Gold on all Challenges.
Weapon Master ( 15 points )	Earn at least Bronze in all the Weapon Challenges.
Weapons Officer ( 20 points )	Use every weapon in the game.