I think the Mario games actually have pretty disturbing over/undertones. Think about the very beginning of SMB for a minute: Mario's just your average, everyday midget Italian plumber on his day to work, when he sees a floating question mark block. Naturally, he decides to smack it with his head, and a mushroom comes out. He eats it, then BAM! He's six feet tall! Suddenly, a crazy-looking walking mushroom with eyes and feet waddles towards him next to a giant green pipe sticking out of the ground. After stomping on the innocent little guy, he goes on a rampage against the trippy denizens of his drugged-up psychosis, eventually embarking on a quest to kidnap the princess. The game is obviously intended to have a disturbing existentialist theme dealing with the darkness of the human soul, or something along those lines.
