According to the 'harcore/casual' false dichotomy I'd be a casual gamer, but it's more accurate to call me a 'midcore' or just 'core' gamer. I lack the patience (and sometimes 'talent') to be a hardcore gamer, but I've played enough games, and do 'try hard' enough sometimes, to do stuff true casuals won't bother learning.
A niche 'indie' core gamer, perhaps, given my interests are narrow and outside of the mainstream often.
I do also play mainstream games though; A triple-A that isn't exactly what I want is probably still going to be better than a shoe-string game that IS made for my kind of player.