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.
Meet with Rhea.
Finish the first trial.
Finish the second trial.
Finish the game.
Listen to the recording from the voice recorder in a secret room.
Escape the theater by killing all the members of the Scarlet Lodge.
Escape the theater without killing anyone.
Examine all objects containing text.
Collect all voodoo figures.
Have sex intercourse for at least 3 minutes.
Press the piano keys 50 times.
Solve the puzzle in the theater with the least number of spins.