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