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.
Spirit-bended 200 dark spirits.
Collected every treasure item.
Purchased 12 talismans.
Went into Avatar State 10 times.
Completed the game on Extreme difficulty.
Collected 10 cabbages.
Completed the highest difficulty of Pro-bending.
Maxed out all bending types.
Obtained all combos.
Performed 100 Finishing Moves.
Won a Face-Off in a Pro-bending match.
Got 10 Knockouts in Pro-bending matches.
Completed Chapter 8.
Completed a Naga Running sequence without hitting anything.
Completed Chapter 7.
Completed Chapter 6.
Dodged 100 times.
Completed Chapter 5.
Countered 100 times.
Went into Clash Mode 10 times.
Completed Chapter 4.
Jumped 100 times.
Completed Chapter 3.
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.