Any form of gaming people go out of their way to play and get good at, as a purpose in life, is hardcore. Casual gaming is for people who don't take seriously and will do when they have some free time, or as a break from the rest of their lives, or as one of multiple activities people do with friends. Casual is pick up and play. Hardcore is master.
Using this definition, Rock Band/Guitar Heroes, and Chess can be seen as hardcore games. This is the diplomatic explaination. To be blunt, hardcore gaming is for people who don't have much of a life, while casual gaming is for people who do have lives.







