Complete the following achievements to unlock Xbox Live Gamerscore points.

Achievement	How to unlock
Back to Retirement ( 20 points )	Defeat Julius Steelwell and save the world by destroying The Butler.
Can't Touch This ( 30 points )	Complete an area in Katharsis without getting hit.
Gladiator ( 25 points )	Clear all Survival mode arenas.
Green Peace ( 10 points )	Don't push over any trees in Trespassers.
Iron Man ( 10 points )	Learn how to operate your walker and complete Bootcamp.
Mine! Mine! Mine! ( 10 points )	Don't take any damage from sea mines in Tide of Battle.
Second in Command ( 15 points )	Defeat General Brutus by destroying The Excavator.
Survival of the Fittest ( 20 points )	Complete a Survival mode arena without losing a life.
Take it to the Max ( 15 points )	Fully upgrade your walker.
Thunder Struck ( 10 points )	Destroy all lightning harvesters in Fog of War.
Veteran ( 25 points )	Complete all areas on the hardest difficulty.
You Never Walk Alone ( 10 points )	Complete an area in co-op.