Here is the full list of all 15 Afterdream achievements.
Complete world one.
Complete world two.
Complete world three.
Complete world four.
Complete world five.
Complete world six.
Complete the game.
Check out the dark bathroom.
Ask the ghost in a red suit about recycling.
Think about burning the owl ice sculpture.
Save the game while Riley examines the save spot.
Admire the mailman's fine mustache.
Read all the writings of the faceless ghost.
Find the familiar jar.
Examine the red hair dye.