If all you play is CoD and Madden (Or Fifa in UK) you are not a gamer in my book, never mind a hardcore gamer
A hardcore gamer is a gamer who plays a WIDE WIDE Variety of games, ranging from retro to modern and plays as one of his main hobbies.
A hardcore gamer in my book is someone who plays ANY type of game. Doesn't have to have gore and blood in it. People who play animal crossing can be a hardcore gamer if they play a ton of other games with it. If all you play is First Person Shooters or sports games, you are not a hardcore gamer, you are a First person shooter fanatic or sports fanatic.
While casual gamers are gamers who only play casual games, candy crush, animal crossing, farmville, puzzle games etc. Just games that everyone can play.
Ohhhh noooo one of these topics.
I think hardcore is how a person plays a game. Let's use Mario Kart for example like I usually do.
Lots of people play Mario Kart casually and just play races to have a little fun by themselves or with friends in person or online. Casual is fine no one should knock it because it's just for fun and that's what games are for.
Now a hardcore Mario Kart player will learn all the tricks in gameplay mechanics, get 3 stars on all cups, beat all the staff ghosts and try and set good records. It is all about how the player plays the game that defines it in my eyes.
Both casual and hardcore are just fine and I do both for certain games. No one should be ridiculed for being a casual gamer or need to feel like the only way they will be considered a gamer is to be hardcore. We all do it to escape and have fun. It doesn't matter.
My sister is a casual gamer, plays no games but stuff like puzzle games, candy crush, farmville, angry birds etc, but she goes for highscores and stuff, beats staff ghosts, 3 starts etc, that doesn't make her a hardcore gamer, she bearly plays games to begin with. Just makes her a completionist