Here is the full list of all 10 The Monster Under Your Skin achievements.
Start the game at least once
Win a teddy bear at the amusement park
Win one of the two main prizes at the amusement park
For some reason, bad luck is following you
Win the plastic ring and propose Irma with it
Successfully find your son three times
Finish the game at least once
When you asked Irma if she agreed to keep the memories, she said 'Yes'
Get a bad ending, while spitting in the characters' faces
Find out all the endings of this game