This is my most favorite game of all time. Other versions are fine, but this app is the most challenging and keeps me entertained for hours. BUT after each upgrade which only comes out maybe yearly, I can not purchase the new puzzles (not expensive and worth the change). I think I wrote to someone last year and it was fixed but this year same problem with no solution. PLEASE fix the the bug that will allow me to purchase the new set both black/ white and color options. Ps I have deleted and reinstalled but no luck, I am replaying old puzzles but I am wanting the new ones. If u like this type of puzzle it's a must have.