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