Andoku 2 is an app that lets you solve Sudoku number puzzles on your smartphone or tablet. The goal of Sudoku is to fill out a grid with the numbers from 1 to 9 so that each number appears exactly once in every row, column and 3×3 block.
The free version of Andoku 2 offers a total of 10,000 puzzles in six different game variations. It is possible to choose from eight levels of difficulty, ranging from very easy to extreme.
There is also a premium version of the game that includes four additional game variations. It offers 15,000 puzzles that differ from those in the free version.
Andoku 2 lets you to choose from three distinct color themes. In addition to the default theme there is a classic theme that resembles the look of the original Andoku Sudoku and a black theme that can be used in low light conditions.
Andoku 2 includes puzzles in six game variations: Standard Sudoku, X Sudoku, Hyper Sudoku, Percent-Sudoku, Color-Sudoku and Squiggly Sudoku. Each variation adds one or more additional restrictions to the game. For example, X Sudoku requires that, in addition to the normal Sudoku rules, numbers cannot be repeated in either diagonal of the puzzle.
The premium version has 4 additional variations: Squiggly X-Sudoku, Squiggly Hyper-Sudoku, Squiggly Percent-Sudoku and Squiggly Color-Sudoku.
Andoku 2 automatically saves the current game when you leave the app so it can be resumed later. Multiple puzzles can be started simultaneously.
The game features unlimited undo/redo and error checking. It allows you to enter notes or candidate values for each cell and it can automatically remove notes that became obsolete when the corresponding value was entered in the same row, column or 3×3 block.
The app lets you choose your preferred method of entering values into the puzzle. With Digit First you first select a digit on the keypad and then assign that value to one or more cells in the grid. With Cell First, on the other hand, you first select a cell and then assign a value. The classic input methods automatically convert a value into a note when you enter more than one digits in a cell.