Here is the full list of all 34 Mary Skelter: Nightmares achievements.
Cleared 10 work orders.
Matured a floor.
Entered Blood Skelter mode for the first time.
Protected the heroine 100 times.
Entered a hidden floor.
Cleared the City Streets area.
Filled the Jail Creature Manual with 10 creatures.
Satisfied the Jail's Sleep.
Satisfied the Jail's Libido.
Satisfied the Jail's Hunger.
Entered Massacre mode for the first time.
Obtained all Trophies!
Cleared the Graveyard area.
Cleared the Temple area.
Cleared the Downtown area.
Cleared the Dorm area.
Cleared the Waterside area.
Cleared the Station Grounds area.
Cleared the Jail Tower.
Cleared the Underground Jail area.
Unlocked the Bad Ending.
Unlocked the Good Ending.
Complete 80% of the Jail Creature Manual.
Hameln joined your party.
Unlocked all of the heroines' jobs.
Collected 100,000 Gold.
Cleared 50% of the work orders.
Blood Devolution reached Level 80.
Defeated all Nightmares outside the Jail.
Gained the Blood ability Mary Reverser.
Conducted Purge for the first time.
Raised one heroine's affection to max level.
Raised all heroines' affection to max level.
Activated a Blood Soul Skill 100 times.