Here is the full list of all 22 Lust from Beyond: Prologue achievements. It takes around 2-3 hours to unlock all of the achievements on Windows.
Read all the letters concerning Mabel and complete all the conversations with her.
Turn of censorship during gameplay.
Finish the game.
Complete the game in censored mode.
Walk through Lusst'ghaa without receiving damage.
Pick up all the touchable items in the game.
Read all the notes.
Look at unconscious Mabel for 3 minutes.
Find and use all the sedatives.
Pick up the devil mask, when the light is out in the mansion.
Look at the cultist orgy for 5 minutes.
Pick up all the masks.
Find and use all the first aid kits.
Talk to the prisoner under the stairs.
Collect all the lauv'abrarc figures.
Open the secret locker in Theodore's bedroom.
Collect all the ritual items.
Pick up all the items in Theodore's room.
Don't show any doubts speaking to the Cult members.
Open the tabernacle with as few moves as possible.
Spend a minute reading prayers from Iauv'abrarc's altar.
Finish the dream about the land of Lusst'ghaa.