Here is the full list of all 10 Tangle Tower achievements. It takes around 6-8 hours to unlock all of the achievements on Windows.
Find three sets of similar research notes
Find your way into the secret room
Talk to the suspects about Tangle Tower
Listen to Poppy's poems
Talk to the suspects about your Case File
Find three statues of a certain amphibious creature
Look at the Family Tree and the drawing board
Find the Tangle Tower snowglobe
Begin investigating Flora's Tower