What is a Casual Game?

[krashed]

'Casual' : This term has come a long way, from a mere adjective it has become a game genre, but I believe it has further evolved beyond just a game genre.

Nowadays, how do you define a "Casual Game"? The most common description I hear of is that the game would be built around a simple core game play mechanic, think Angry Birds and Bejeweled.

A friend asks me, "If angry bird causes you to play it for hours non-stop, is it still casual?". If a game with complexities like a RPG would have (stats builds, skill trees etc) but at the same time allows me to put it down anytime, is that casual? How much complexity can you add to a "simple game" before it is no longer considered "simple" or "casual"?

Another friend tells me that "It is a matter of players' perception". Then would that not make "casual" an equivalent to the term "fun" ? If this is the case, you can no longer say "I am going to design a casual game!" as that would equate to you saying "I am going to design a fun game!", but is this the actual case?