Here is the full list of all 45 Fhtagn - there are Tales of the Creeping Madness achievements.
Successfully perform the Omen role in the Dreaming Eye cult
Successfully perform the Sacrifice role in the Dreaming Eye cult
Successfully perform the Grimoire role in the Dreaming Eye cult
Successfully perform the Ceremony role in the Dreaming Eye cult
Successfully perform the Ritual Instrument role in the Dreaming Eye cult
Successfully perform the Sacred Relic role in the Dreaming Eye cult
Successfully perform the Defence role in the Dreaming Eye cult
Successfully perform the Traitor role in the Dreaming Eye cult
Successfully summon the Great Dreamer
Play a game with more than 1 character and win
Gain victory as a Traitor in a game with more than 1 character
Stop the Traitor in a game with more than 1 character and win
Have 14 Body, by the end of the game
Have 14 Performance, by the end of the game
Have 14 Knowledge, by the end of the game
Have 14 Magic, by the end of the game
Have 14 Sanity, by the end of the game
Have 14 Insanity, by the end of the game
Have 14 Influence, by the end of the game
Have 20 Riches, by the end of the game
Win 6 Riches in a single Gamble action at Madame Fufu's
Destroy a building
Cause a building to be locked down by the Police
Disable the maximum number of buildings and options allowable for a single game
Escape being sacrificed with the help of a Henchman
During the Sacrifice Phase, successfully sacrifice a Provided Sacrifice item
Successfully escape being sacrificed
Take part in an encounter with a Dark Young
Successfully summon the All-mother
Have 6 or more stacks of Not It! by the end of the game
Successfully sacrifice a player character
Kill a Dark Young
Gain an item, henchman or buff
Have a Dark Young at every location, by the end of the game
Have no Dark Young in town, by the end of the game
Successfully perform the Omen role in the Thousand Young cult
Successfully perform the Grimoire role in the Thousand Young cult
Successfully perform the Ceremony role in the Thousand Young cult
Successfully perform the Ritual Instrument role in the Thousand Young cult
Successfully perform the Sacred Relic role in the Thousand Young cult
Successfully perform the Defence role in the Thousand Young cult
Successfully perform the Traitor role in the Thousand Young cult
Summon the All-mother without a sacrifice
Successfully use the Handgonne of St Augustine during the Ritual
Successfully use Black Annis' Claws during the Ritual