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