The Industry definition of the casual games genre includes games that focus on brain teasers and short play sessions: Minesweeper, MS Solitaire, Frogger, Freecell, Farmville, and Brain Age. The genre was coined by Namco when it released Pacman back in 1980, and later re-iterated by Nintendo to classify Brain Age.
Mario is a platformer, Zelda is an action adventure, Mario Kart is a racer, Pokemon is a light RPG/console RPG, Monster Hunter is an action game. None of those are in the casual games genre.
There is no such thing as a "hardcore game". That's mostly just a term that a portion of gaming fans use to make the games they play sound "badass" (and not just fans of bloody/violent games either, but also Mario and Zelda fans); the genre doesn't actually exist - and the term is really just pretentious.
In fact, most of the time when I hear the term "hardcore", it is used by very nerdy people to describe their hobbies - especially the music they listen to and the games they play. The term "Hardciore" is used in an attempt to artificially elevate their hobbies; and in extension, elevate themselves to a socially higher position than where they actually truly exist.
I describe myself as a little dose of toxic masculinity.
