I would say it depends on your interest level. I do think there is a middle ground involved, but I think you tend to sway closer to one way than another. Sadly, yes, you can be a hardcore farmville gamer. There are people out there spending alot of money on farmville cash and are insane over it. 2 women in my family are this way minus the transactions. But they religiously log in every day (usually more than once) to tend to their farm and send gifts to well over 20 people. This amount of effort I would say ties (if not surpasses) the amount of effort I put into gaming.
I consider myself a hardcore gamer of these two. I do not care for the film industry much and as such my games are my source of preferred media entertainment. I play games at least 4 hours a day on average, maybe more. I know about the games I play typically and the time I spend not playing them in recreation is usually spent learning about them. I am not talking about cheat codes or anything but rather looking over various reviews, press coverage, keeping an eye on multi-platform releases (including the ones I don't own), etc. Gaming is a passion of mine much like someone who has a passion about the film industry.
Let's put it this way, if you can list 5 game developers and 3 games made by each you have stepped into hardcore gaming. If not you are a casual gamer. I personally use the term "hardcore" as a reference to someone who knows about the buzz floating around in the industry. Very little gets past my radar about upcoming releases in video games. I think the term "hardcore" and "fanboy" are not proper terminology and misleading through intent. The term "gamer" is too vague anymore because "gamer" has sort of become a 'coolness' tag. There should be a term for "gaming connoisseur" as hardcore vs. casual gamer is more in playstyle preference and really speaks too vaguely of your actual industry interest. I am more inclined to listen to a fellow "gaming connoisseur" than I am just some guy who plays a game or two on the weekend.
If all you play is farmville or bejeweled or COD, then you are a fan, not a hardcore gamer. Although alot of people that play COD, Bejeweled, etc. can't even tell you who publish the game and still claim being a "hardcore player" as opposed to being a "hardcore fan".