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.
Completed all tutorials.
Collected every treasure item.
Collected 10 cabbages.
Went into Avatar State 10 times.
Spirit-bended 200 dark spirits.
Completed the game on Extreme difficulty.
Purchased 12 talismans.
Completed the highest difficulty of Pro-bending.
Maxed out all bending types.
Performed 100 Finishing Moves.
Won a Face-Off in a Pro-bending match.
Got 10 Knockouts in Pro-bending matches.
Obtained all combos.
Completed a Naga Running sequence without hitting anything.
Completed Chapter 8.
Completed Chapter 7.
Completed Chapter 6.
Completed Chapter 5.
Used your first equipped item.
Completed Chapter 4.
Dodged 100 times.
Equip your first item in Korra's Room.
Went into Clash Mode 10 times.
Countered 100 times.
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.