Today I just finally finished all the challenge of 12 Series duels races without any purchased and throw money inside this games. I now have the balanced of 2.3billion of coin money.The Series 12 more difficult level for me, I almost spend 3 week to finished 1100 point of series 12. I have been faced the obstacle during from 800 point drop 300++ point, at that time I feel disappointed, but later slow growing back the point to 800++ yesterday, then I become careful to prevent drop back the point.