Here is the full list of all 17 Backworlds achievements.
Leave the Cave
Make progress all over the world
Find home and use the color changer
Overcome the head of the forest
Overcome the airship engine
Overcome the spirit at the bottom of the sea
Overcome the engineer in the city
Reach the end
Reveal the whole map
Solve all of the puzzles
Achieve maximum separation of head and body
Everybody needs a friend
Reach the ending sequence in less than 60 minutes
Reach the ending sequence before jumping more than 270 times
Find everything in the forest without using a reset switch
Only teleport once in the engine room
Keep the blue flames low when overcoming the spirit