I am asking this because I do have some short of an answer for videogames and for massive multiplayer games and even for social network oriented games. Videogames require a great design, good difficulty grading, an story that engages the user, massive multiplayer and network oriented are a lot about the interactions and how varied and fun these are. However, for casino games, it would seem that these factors are not really the most important ones. You can see games with very basic graphics and design, simple in the options for the player and not that engaging yet they do "hook" people in them.
What do these games have to have for you?
In gambling, the general atmosphere and interface are very important for me.
Gambling is primarily a game.
I want to feel like a space tramp and adventurer Jason Di Alt (the hero of Harry Harrison's novel "Indomitable Planet") or James Bond from the movie "Casino Royale" or D'Artagnan (the hero of Alexander Dumas's novel "The Three Musketeers").
It's just so boring to play.
I would like to feel like the savior of the whole planet, a super agent, or at least an eternally drunk nobleman from the detachment of the guards of His Majesty King Louis XIII.