Sudoku is played on a playing board consisting of a grid of 9×9 spaces.
The game has three different game modes: Classic, Point and Battle. In each mode, every row, column and square needs to contain the numbers 1-9, without repeating any numbers within the row, column or square. By using logical thinking, it is possible for the players to figure out which numbers from 1-9 are missing in the empty spaces. When the players have decided on a number to put in an empty space, they simply need to use the numbers keyboard in front of them and drag and drop the chosen number to the empty space.

Classic

In this classic game mode, the playing area contains two different Sudoku puzzles that are played independently of each other.

Deleting and editing numbers:
When playing the classic version, players do not receive instant feedback from the game whether or not the number that they have placed in the empty space is correct or incorrect. This will only be revealed once there are no empty spaces left on the playing board. This also means that the players can edit a number at a later stage of the game if they should change their minds. If the players want to delete a number that they have filled in earlier in the game, they simply need to drag and drop the red X to the space which will then become empty again, and the players can fill this space with a new number. If the players already know which number they want to replace the current number with, they can also simply drag and drop this number onto the space and the old number will be replaced by the new number.

Hints:
Unlike the other two game modes, in the classic version, it is possible for the players to get help from the game. If they drag and drop the box with the question mark to one of the spaces that the players need to fill in, the game will turn this space purple and reveal the correct number.

End of the game:
After filling in the last of the empty spaces on the board, all spaces containing numbers that the players have selected will either turn red or green. A red space means that this number is incorrect, whereas any space turning green means that the number is correct. Any purple spaces contain numbers that the players have asked the game to fill in for them.

Point

In this game mode, the playing area consists of two identical Sudoku puzzles next to each other, and the players need to work together to not only solve the puzzle but also achieve the highest possible score. 

Meaning of the colours:
Every time an incorrect number has been placed in one of the empty spaces, this space turns red and will stay red until the players have replaced the incorrect number with the correct one. Depending on which player/team placed the correct number, any space where the players have inserted a correct number will turn either green or turquoise. 

Point system:
For each correct number, the players are rewarded with 100 points. However, for each incorrect number that the players insert, their score is deducted by -500 points. This underlines the importance of good communication between the players and making sure that each move is correct in order to achieve a good score. At all times during the game, the players’ score will be visible in the middle of the playing board.

Battle

In the Battle mode, the playing area displays two identical Sudoku puzzles next to each other. The game is played with two teams competing to conquer the most territory. 

How to conquer the board:
When a team is first at filling out an empty space with a correct number, that space turns into the colour of this team (either green or turquoise). Also, if a team inserts a wrong number into an empty space, the team loses this space to the other team. The game shows this by initially turning the space red (indicating a mistake) and then, shortly after, changing the incorrect number into the correct number and the red colour into the colour of the opposing team.
In the course of the game, it is possible for a team to win back lost spaces on the board. Every time a square (3×3 spaces), a row or a column has been completed, the game awards this entire area of spaces to the team that has conquered the most of the spaces inside the area. If both teams have conquered an equal amount of spaces, the entire square, row or column is awarded to the team that conquered the last of the empty spaces. 

End of the game:
When all empty spaces have been filled in by the teams, the game is over. The team that managed to turn the most spaces into their team colour has won.