Full list of all 12 Gatling Gears achievements worth 200 gamerscore. It takes around 10-12 hours to unlock all of the achievements on Xbox 360.
You stood against many and survived
You survived an Empire offensive without needing to restart your walker
You completed part of the adventure with a wingman
You mastered the basics of walker operation
Complete an area in Katharsis without getting hit
Defeat Julius Steelwell and save the world by destroying The Butler
Complete all areas on the hardest difficulty
Defeat General Brutus by destroying The Excavator
Fully upgrade your walker
Don't push over any trees in Trespassers
Destroy all lightning harvesters in Fog of War
Don't take any damage from sea mines in Tide of Battle