Never any pop-up or forced advertising. Sudokus are provided Daily in Easy, Medium, and Hard difficulty levels. The Difficulty Levels are based on how solving the puzzles and Not on how many squares are populated when you start. So.. a really great grading system for puzzles. Then there are also books that exist in Full Page 8.5 x 11 inch format, which have codes that can be plugged into the SudokuEverywhere App and then played on what ever device is available. In other words, these puzzles should work Everywhere you may want to play them … iPad, iPhone, Android Phone, Android Tablet, Personal Computer, Notebook, etc.