Here is the full list of all 18 Gray Dawn achievements worth 1,000 gamerscore. It takes around 2-3 hours to unlock all of the achievements on Xbox One.
Find the icon from Dream Forest!
Find the icon from Rosendorf Cemetery and release the spirits of the dead children!
Find one of the three icons from The Little Prince Orphanage!
Find the icon from The Mysterious Island!
Follow Alexander and find another icon!
Relive the terrifying night of the exorcism.
Unlock the "happy" ending.
Unlock the "bad" ending.
Find another icon in Rosendorf Cemetery!
Find an icon hidden in a peculiar place around The Little Prince Orphanage.
Find the first audio cylinder.
Find the second audio cylinder.
Find the third audio cylinder.
Find the fourth audio cylinder.
Find the fifth audio cylinder.
Listen to all the audio recordings.
Meet Alexandra from beyond the grave.