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