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