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.
Complete Chapter 2
Ring the reception bell 10 times
Ring the reception bell
Complete Chapter 1
Complete Chapter 3
Complete Chapter 4
Complete Chapter 5
Complete Chapter 6
Complete Chapter 7
Complete Chapter 8
Complete Chapter 9
Complete Chapter 10
Find the birthday room.
Find the first of Ada's notebooks
Find the second of Ada's notebooks
Find all of the pneumatic tube messages
Find all collectibles in Chapter 1
Find all collectibles in Chapter 2
Find all collectibles in Chapter 3
Find all collectibles in Chapter 4
Find all collectibles in Chapter 5
Find all collectibles in Chapter 6
Find all collectibles in Chapter 7
Find all collectibles in Chapter 8
Find all collectibles in Chapter 9
Find all collectibles in Chapter 10
Complete the game