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