Here is the full list of all 56 Little Walker achievements.
Level up
I get knocked down! but I get up again!
I hope you're proud of yourself
Myup that was dookie
Get a plusm
Get spoken to by any character
Get an achievement
Fail to get back up
Hi again!
Defeat 100 enemies
Ate the trashcan sandwhich
Get 64 plusms
Use the air breaks
Flipped the day/night switch
Ran on hot coals for a while
Ate one of those red berries
Walk 500 miles
Walk 500 more
Jump 1000 times
Pick up the rock
Squish the fly
Talk to the funky seagull
Disturb the penguins
Straight up murder Carl
Meet the moleman
Kick a dude in the head
Pop 99 balloons
Conquered the cliff
Touched the apple wife (sadly she had apple-butt)
Dancing in the desert blowing up the sunshine
Discovered the desert birds burrow
Enter the pyramid
Ring the bell above the abandoned mission
Drank the very last swig that was just sittin there
Straight up murdered a majestic creature of the sky
Found spocker
You just have to keep eating food that's been sitting around, don't you?
Straight up robbed some dudes tomb
Found the invisible block
Walked on the rainbow bridge
Rode the golden dragon
Felt the mighty power of the monoforce
Read the sign you shouldn't have
Beat the game on either mode
Beat the game on auto-walk mode
Did the training room
Found moon mode... Oi.
HAPPY FEET, THAT AIN'T FALCO
Found a shortcut
Unlock 7 blocks
Discover the weirdos
Found the legendary baby coin
Went to the bathroom maybe?
Beat the game without hitting 0 hp
Discover that one place
Beat hard mode!