Today marks the annual celebration of one of the most iconic video franchises and characters of all time. What Happened: Mario Day is celebrated annually on March 10. The holiday celebrates one of the bestselling video game franchises of all time with a unique take on the calendar day. The date March 10 written in abbreviated form spells out Mario, with the “1” and zero replaced by the letters “I” and “O.” Nintendo Co (OTC:NTDOY) which owns the franchise, began celebrating the holiday in 2016. Mario made his debut in the 1981 video game “Donkey Kong.” Nintendo would give Mario his own game wit…