Here is the full list of all 37 King of the Hat achievements.
Open the game
Play 5 multiplayer games
Play 10 multiplayer games
Play 20 multiplayer games
Play 50 multiplayer games
Play 100 multiplayer games
Play 200 multiplayer games
Beat Golf with Birthday
Beat Golf with Kiara
Beat Golf with Fatcat
Beat Arcade Mode
Beat Arcade Mode on Hard
Unlock all levels of Hatlandian Hills
Unlock all levels of Kiara's Castle
Unlock all levels of Cole's Place
Unlock all levels of Shrines of Hat
Unlock all levels of The Void
Unlock all levels of Hat Factory
Unlock all levels of Cloud City
Unlock all levels of Fatcat's Office
Unlock all levels of Super Hat Con
Unlock all characters
Join a friend online
Unlock all item blocks
Make $1,000,000 Money
Make $100,000 Money
Make $250,000 Money
Make $500,000 Money
Make $750,000 Money
Complete the Tutorial
Crush 3 hats in a row
Crush 5 hats in a row
Crush 8 hats in a row
Crush 11 hats in a row
Win 5-0 in a 1v1 in Last Hat Standing
Play at 50% game speed
Play at 150% game speed