Here is the full list of all 17 Koala Kids achievements.
Get the first hat.
Meet the banker for the first time (At the end of the level).
Hide in a bush.
Complete the game in single player. Not necessary to unlock every item.
Complete the game in single player, unlocking everything.
Complete the game in coop. Not Necessary to unlock every item.
Complete the game in coop, unlocking everything.
Collect 8000 total treasure in a world.
Play game for 10 min in one session.
Use a snare trap.
Unlock all the flowers.
Finish building the house.
Get all the hats.
Use a dynamite.
Use a water bucket.
Unlock all band members.
Lose 20 treasure on death.