LARGE BUTTONS. Tap number twice to ERASE.
Multiple Grid Sizes. 4x4. 5x5. 6x6. 7x7. 8x8.
If you have never heard of KenKen or CalcuDoku it is an awesome Sudoku Variant.
Here is a summary of the rules.
1. Complete the grid such that every row and column contains the digits 1 to the size of the grid.
2. Each row and column contains each digit only once.
3. A colored clue tells you the answer after the same color values have undergone the specified mathematical operation.
4. The clue doesn't tell you which way around the digits occur, just the answer to the calculation.
5. A digit may appear more than once in a color.