Here is the full list of all 30 The Legend of Korra achievements. It takes around 15-20 hours to unlock all of the achievements on Windows.
Collected every treasure item.
Completed the game on Extreme difficulty.
Collected 10 cabbages.
Spirit-bended 200 dark spirits.
Purchased 12 talismans.
Obtained all combos.
Completed a Naga Running sequence without hitting anything.
Went into Avatar State 10 times.
Completed all tutorials.
Completed the highest difficulty of Pro-bending.
Maxed out all bending types.
Won a Face-Off in a Pro-bending match.
Got 10 Knockouts in Pro-bending matches.
Completed Chapter 8.
Completed Chapter 7.
Countered 100 times.
Performed 100 Finishing Moves.
Completed Chapter 6.
Completed Chapter 5.
Used your first equipped item.
Went into Clash Mode 10 times.
Completed Chapter 4.
Dodged 100 times.
Equip your first item in Korra's Room.
Bought your first item at the shop.
Completed Chapter 3.
Jumped 100 times.
Entered the Collection Screen for the first time after finding a treasure.
Completed Chapter 2.
Completed Chapter 1.