Also see this interview http://us.wii.com/iwata_asks/nsmb/vol1_page1.jsp for how Mario was conceptualized. A lot of the functionality and visual features were due to constraints in the gaming systems back then and clever UX designs. E.g. why Mario wore overalls or why he's even a plumber.

Even if I am not a very avid gamer I am definitely a fan of Nintendo. Super Mario World was one of the first video games I played and the Super Mario video games are some of the best games ever released.