Here is the full list of all 20 New York Mysteries: Secrets of the Mafia achievements.
Completed the main chapter on Hard mode.
Completed the symbol plates mini-game without excess clicks.
Completed a hidden object scene without random clicks.
Clicked more than three times in one second in a hidden object scene.
Completed the main and bonus chapters without skipping mini-games.
Completed the main and bonus chapters without using hints in hidden object scenes.
Completed the main and bonus chapters without skipping dialogs or movies.
Completed the spot the difference mini-game without making a mistake.
Completed all collections.
Completed the casino chip collection.
Collected all the phantom objects.
Completed the tie collection.
Completed the statue of liberty collection.
Arranged the books showing the presidents' portraits in chronological order.
Completed the briefcase collection.
Completed a trip in the underground city.
Completed 3 mini-games in a row without using the Skip button.
Completed a mini-game in more than 5 minutes.
Completed a mini-game in less than a minute.
Found 3 items in 3 seconds in a hidden object scene.