Full list of all 12 Undertow achievements worth 200 gamerscore. It takes around 15-20 hours to unlock all of the achievements on Xbox 360.
Achievements they've won
Achievements they've not won
Get 100 kills. Unlocks a Gamer Picture!
Complete the Hope of Humanity Campaign
Complete the Nemo's Wrath Campaign
Complete the Atlantis Rising Campaign
Complete each chapter in co-op mode
Take over 100 control points
Complete each chapter on Ultra
Upgrade all units to level 3 in a single ranked match
Win a ranked Conquest match by taking all of the control points (get a shutout)
Get 200 depth charge kills
Upgrade all units, all races to level 3
Get 10,000 kills. Unlocks a Gamer Picture!