Here is the full list of all 39 Rainbow Billy: The Curse of the Leviathan achievements.
Break the Curse of the Leviathan and save the World.
Accept your other self and befriend Shadow Billy.
Raise 30 creatures' friendships to Level 2!
Glide using the Billy-Copter for more than 5 straight seconds!
Face your fears and befriend Calypso.
Collect 25 Thoughts.
Discover the broken warp pipe.
Catch 10 non-gummi items while fishing.
Fight toxic masculinity and befriend Dragalant.
Flawlessly complete a difficult "Dodge" attack minigame!
Dig up 15 buried treasures.
Flawlessly complete 50 attack minigames!
Collect 10 Thoughts.
Flawlessly complete a difficult "Paddle" attack minigame!
Recolor five colors in one blow!
Raise 5 creatures' friendships to Level 2!
Flawlessly complete a difficult "Line" attack minigame!
Flawlessly complete a difficult "Circle" attack minigame!
Destroy 25 Objects!
Catch three different objects in one fishing session!
Flawlessly complete a difficult "Slots" attack minigame!
Convert a Thought into a Figment of Imagination!Service.
Listen to Friend-Ship whistle for more than 5 straight seconds.
Raise 20 creatures' friendships to Level 3!
Raise 40 creatures' friendships to Level 3!
Befriend all creatures.
Raise ALL creatures' friendships to Level 3!
Catch at least one of each kind of fish!
Fast travel between two distant areas of the World.
Get reprimanded for punching barrel-kind.
Hear each and every one of the The Confessor's secrets.
Talk to all Kickstarter Backers characters!
Discover Disco Broccoli!
Climb to the highest point in each area of the World.
Peek through the window...
Collect 50 Thoughts.
Collect 75 Thoughts.
Collect ALL Thought Upgrades!
Own 500 coins or more.