Here is the full list of all 14 Twisty's Asylum Escapades achievements.
Achieving steam by opening up the steam pipe.
Killing an enemy in the water.
Kill 10 janitors.
Getting all five of the multiplier of a single poster.
Getting five different posters each up to their maximum multiplier number.
Five sneak attack bite 'n shake deaths.
Get one of your minions, a human enemy and an evil ghost to all fight each other simultaneously.
Get a poster that requires you to jump onto another object or surface.
Cause an enemy to slip in a pool of blood.
Play the piano.
Defeat an enemy ghost without getting hit.
Defeat one of every enemy without getting hit (except for bosses).
Beating the game.
Reach the level cap.