Here is the full list of all 27 Close to the Sun achievements. It takes around 6-8 hours to unlock all of the achievements on Windows.
Find all of the pneumatic tube messages
Find all collectibles in Chapter 4
Ring the reception bell 10 times
Find all collectibles in Chapter 3
Complete the game
Complete Chapter 10
Find all collectibles in Chapter 10
Complete Chapter 9
Find all collectibles in Chapter 9
Complete Chapter 8
Find all collectibles in Chapter 8
Complete Chapter 7
Find all collectibles in Chapter 7
Complete Chapter 6
Find all collectibles in Chapter 6
Find the second of Ada's notebooks
Complete Chapter 5
Find all collectibles in Chapter 5
Complete Chapter 4
Complete Chapter 3
Find the first of Ada's notebooks
Find the birthday room.
Complete Chapter 2
Find all collectibles in Chapter 2
Ring the reception bell
Complete Chapter 1
Find all collectibles in Chapter 1