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.
Completed the game on Extreme difficulty.
Collected every treasure item.
Collected 10 cabbages.
Obtained all combos.
Spirit-bended 200 dark spirits.
Purchased 12 talismans.
Performed 100 Finishing Moves.
Went into Avatar State 10 times.
Completed the highest difficulty of Pro-bending.
Completed a Naga Running sequence without hitting anything.
Maxed out all bending types.
Got 10 Knockouts in Pro-bending matches.
Countered 100 times.
Won a Face-Off in a Pro-bending match.
Completed Chapter 8.
Completed Chapter 7.
Completed Chapter 6.
Completed Chapter 5.
Completed Chapter 4.
Went into Clash Mode 10 times.
Dodged 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.
Jumped 100 times.
Completed Chapter 1.