Wii Fit is the fifth best-selling game in history with more than 18 million copies sold before April 2009 , within less than two years of its launch .
Within a year of it 's release it became the 5th best selling game of all-time with 18.22 million copies sold as of March 31 2009 .The balance board measures a user 's weight and center of balance .
Wii Fit