Here is the full list of all 54 Last Light achievements.
Cleared the LIGHT mode.
Obtained Claudia's student ID.
Placed salt 10 times.
Obtained Hunter's student ID.
Collected all of the Fire Demon's diaries.
Opened all locked doors.
CHECKED a dead body for the first time.
CHECKED a hidden door for the first time.
Collected all of the diaries of the hospitalized children.
Obtained a surgical instrument for the first time.
Ran into a Fire Demon for the first time.
Obtained Morgan's student ID.
Collected all of the Banshee's diaries.
Obtained a bloody doll for the first time.
Obtained May's student ID.
Died 10 times.
Died for the first time.
Found the Bloody Locker.
Ran into the Banshee for the first time.
Obtained Ralph's student ID.
Tried to obtain an item while already having something in possession.
Hid in a locker 10 times.
Placed 10 candles.
Found 50 items.
Viewed all photos of the directors on the 1st floor.
Obtained Amelia's student ID.
Encountered bloody hand prints for the first time
Refreshed from drinking a delicious beverage.
Sickened from drinking a beverage.
Experienced a door closing on its own.
Opened a restroom stall door for the first time.
Ran into a wraith for the first time.
Obtained Lumi's student ID.
Used a key for the first time.
Used salt and a candle for the first time.
Viewed all photos of the directors on the 2nd floor.
Viewed all photos of the directors on the 3rd floor.
Died from drinking a beverage.
Obtained the carrot diary.
Collected all of the wraith's diaries.
Cleared the DIM mode.
Cleared the DARK mode.
Killed by Mask.
Killed by Louis.
Killed by Ellie.
Killed by Charley.
Killed by Leah.
Killed by AVa.
Managed to hide in a locker while wounded.
Relit the flashlight 10 times.
Obtained a bloodstained student ID.
Chose a Rabbit without a knife during the hide-and-seek event.
Met Rabbit for the first time.
Obtained a repair tool for the first time.