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.
Complete all areas on the hardest difficulty
You stood against many and survived
You survived an Empire offensive without needing to restart your walker
Complete an area in Katharsis without getting hit
You saved the world and can get back to drinking tea and growing pumpkins
You created the ultimate fighting machine
You managed to steer clear from sea mine shrapnel
You have dealt a critical blow to the Empire's power supply
You defeated Julius Steelwell's right hand man
You have proven to be very environmentally friendly
You completed part of the adventure with a wingman
You mastered the basics of walker operation