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