Casual gaming is about the complexity of the games you enjoy. It's the engine, the controls, etc. all of that. That is also the dividing line of comparing smart phones/tablets to consoles. Yes you can play casual or complex games on both but the hardware usually lends to: Mobile/tablet = simpler games, Console/PC = complex. My mom may play the hell out of Candy Crush but is still considered a casual due to the complexity of the game she enjoys. I had her try my PS4 once and the number of buttons on the controller drove her away.