The legal framework
The Penal Law 5737-1977, Chapter 12 ("Prohibited Games, Lotteries and Bets"), bans running a prohibited game, operating a venue for one, and participating in one. A "prohibited game" is defined as a game where a person may win money or money\'s worth, and the chances of winning depend more on luck than on understanding or skill.
This definition is the central axis — it is what separates a classic casino game from games where skill is decisive.