Here is the full list of all 55 Phantasmal achievements.
Opened five locked cases
Fully upgraded flares.
Fully upgraded health.
Fully upgraded keys.
Fully upgraded sneak.
Fully upgraded sanity.
Fully upgraded sprint.
Fully upgraded pistol ammo.
Killed a creepy kid!
Killed a Starver
Completed Level Two
Killed a spitter
Killed a junkie
Completed Thread One
Completed Level One
Killed a group of spiders
Fifty Starvers and still counting!
Opened fifty locked cases
Completed Level Three
Completed Level Four
Completed Level Five
Twenty Five starvers!
Killed fifty junkies
Killed a hundred junkies
Killed ten spitters
Killed thirty spitters
Killed five creepy kid!
Killed twenty creepy kids!
Killed a shadowman
Killed five shadowmen
Killed ten shadowmen
Killed a shadowhound
Killed three shadowhounds
Killed eight shadowhounds
Completed Thread Two
Completed Thread Three
Completed Thread Four
Found all story thread one's notes!
Found all story thread two's notes!
Found all story thread three's notes!
Found all story thread four's notes!
Found five secret rooms
Found fifty secret rooms