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