The board sizes range from 5×5 to 8×8. There are also 3 levels of difficulty: 1-9, 2-4, and 1-19. 1-9 means the numbers to calculate will range from 1 to 9.
There are 2 game modes: Classic and Endless. In Classic mode you can choose which board size and difficulty you want to play. In Endless mode you will be given a puzzle with random size and difficulty. Your total wins in any mode will be recorded. The puzzle is randomly generated so you’ll never get bored of playing.