Here is the full list of all 37 Demetrios - there are The BIG Cynical Adventure achievements.
Get all the game cookies
Order Sandra to lick the statue
Insult the statue in the last room
Sandra write insults about the hotel
Refuse to help Henri
Experience half of the Game Overs
Turn the wheel and die
Finish the game
Create a clone of Bjorn and Caroline
Finish Chapter 5
Win 10,000 points on the pinball tombstone
Get rid of Caroline
Finish Chapter 4
Eat 3 rotten things on the floor
Die 10 times
Put the entire plant in the sorcerer's glass
Spill all the water in the container at the museum
Finish Chapter 3
Finish Chapter 2
Get half of the game cookies
Get all funfair items
Win the Pet Shoot trophy
Win the Plate Shoot trophy
Win 1,000 coins at the funfair
Win all the plushes at the funfair claw machines
Win 100 coins at the funfair
Win the Horse Race trophy
Win the Worm Race trophy
Finish Chapter 1
Use at least 10 cookies
Do dirty things at the police station
Experience all of the Game Overs
Sandra insults her parents in her postcard
Fall from the roof accidentally
Decide not to commit suicide after being poisoned
Try disturbing things on Henri
Forget to close the faucet before leaving Paris