In addition to standard sudoku puzzles it offers these variants: * X-Sudoku * Hyper-Sudoku * Percent-Sudoku * Color-Sudoku * Squiggly Sudoku (a.k.a. Jigsaw Sudoku) * ... and combinations thereof (e.g. Sudoku-X with jigsaw regions) The Google Admob library in the source code of this app has been replaced with a dummy library that does nothing.