Everyone has bought Mario galaxy because EVERYONE knows who Mario is. Also it's the second best rated game of all time.
My Grandmother know who Mario is. My cousin knows who Mario is... and the Wii is the first videogame system he's had. (The age between my dad and his brother was... well i'm closer in age to his brother then he is.)
Mario is the Superman of cartoons. The second most well known character is probably like... Lara Croft.
Everyone else is likely a bit pile of "no clue."