Here is the full list of all 26 Children of Silentown achievements. It takes around 8-10 hours to unlock all of the achievements on Windows.
Collect the "Doll" sticker.
Get the cat as best friend.
Collect the "Flower of hope" sticker.
Collect the "Huge Snail" sticker.
Collect the "Old kettle" sticker.
Collect the "Mysterious footprints" sticker.
Choose the Song of the World.
Collect the "Broken toy" sticker.
Choose the Song of the Forest.
Choose the Children's Song.
Collect the "Mysterious paintings" sticker.
Choose the Mom's Song.
Collect the "Windmill" sticker.
Collect the "Glass shards" sticker.
Get one of the children as best friend.
Collect the "Blue's drawing" sticker.
Collect the "Big metal ruler" sticker.
Collect the "Complicated padlock" sticker.
Collect the "Coal's fur" sticker.
Collect the "Depths of the well" sticker.
Collect the "Hairball" sticker.
Collect the "Puppy" sticker.
Collect the "Trumpet" sticker.
Collect the "Spyglass" sticker.
Collect the "Egghead Lucy" sticker.
Collect the "Lucky charm" sticker.