Here is the full list of all 12 Lust from Beyond: Scarlet achievements. It takes around 1-2 hours to unlock all of the achievements on Windows.
Escape the theater without killing anyone.
Examine all objects containing text.
Solve the puzzle in the theater with the least number of spins.
Listen to the recording from the voice recorder in a secret room.
Finish the game.
Escape the theater by killing all the members of the Scarlet Lodge.
Collect all voodoo figures.
Finish the second trial.
Have sex intercourse for at least 3 minutes.
Finish the first trial.
Meet with Rhea.
Press the piano keys 50 times.