Here is the full list of all 32 Knuckle Sandwich achievements.
Get an A Rank in the Diner minigame.
Echo.
Beat the Exterminator minigame.
Beat the Space Cleaner minigame.
Beat the Dancer minigame.
Get an A Rank in the Cooking minigame.
Make him mad.
Gotta find 'em all.
YEEEEEEEOOUCH!
Earn their respect.
Hate the planet.
No wrong answers.
Time for a visit.
Run into some familiar faces.
Thea.
Dolus.
Brightside.
What are you doing?
Someone had to do it.
A chance encounter.
Find Challenge Mode.
Beat the game in Challenge Mode.
Get an S Rank in Fortunate UFO Collection.
Get an S Rank in Can I Survive this Endless Jogging Fantasy?!
Get an S Rank in The Very Hungry Yeti.
3AM Challenge.
Amazing.
I told you not to eat that!
Find every decoration for your home.
Beat the game.
Leave no stone unturned.
You can do it.