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