Here is the full list of all 41 Labyrinth City: Pierre the Maze Detective achievements.
Get all the Achievements in game.
Find Pierre's twin sister.
Shoot both fireworks.
Catch 5 ducks.
Get on the roof of a car.
Search all the bushes in the Museum.
Press M to "open map".
Catch Mr X... or not.
Finish the Final Giant Maze with all its collectibles.
Get all the Stars.
Get all the collectibles in game.
Find Hoshi in all levels.
Get all the Pages from Mr X's Book.
Get all the Trophies.
Find the Polar Bear in all levels.
Get all the Chests.
Find Gmlf in all the levels (apart from the Haunted Manor).
Find Waldo.
Find Coco in all levels (except at the Southern Castle).
Launch the real Golden Hen's rocket.
Finish the Flea Market level with all its collectibles.
Find where the pink animals come from.
Finish the On the Docks level with all its collectibles.
Find the man who has seen the seabed maze.
Lock yourself behind the door that leads nowhere.
Finish the The Forgotten City level with all its collectibles.
Walk 10,000 steps.
Throw the rock into the sea.
Lock yourself in the cage.
Finish the Haunted Manor level with all its collectibles.
Shock Dr Frankenstein's creature 5 times.
Finish the Village in the Forest level with all its collectibles.
Find out whether the chicken or the egg was first.
Finish the Southern Castle level with all its collectibles.
Grow the magic bean.
Listen to everything he has to tell you.
Find Pierre's strange double.
Finish the Downtown level with all its collectibles.
Finish the Street Party level with all its collectibles.
Finish the Museum level with all its collectibles.
Change an option in the option menu.