Ultimate Sudoku is a classic online game for training the brain and thinking. The player sees a square of 9x9 cells on the playing field, divided by smaller squares. Each cell should have its number, but on condition that it is not repeated either in a row, in a column, or in the 3x3 square itself. Fill in the empty squares with numbers from 1 to 9, where each of them occurs only once. This free puzzle game has only one solution! Everything will depend only on the ingenuity and observation of the player. Change backgrounds, enjoy different difficulty levels, and challenge yourself with this online game!