About Ultimate Sudoku GameUltimate Sudoku is a fun online version of Sudoku featuring 3 difficulty levels: beginner, intermediate, and advanced. Select a cell with a number in it and it will highlight all the cells with that number in it. Select an empty cell and then tap one of the number buttons at the bottom to enter that number. If you attempt to make an invalid play an associated number tile which invalidates the play will appear in red. Tap the button one in from the right in the bottom row to place a hint, and tap it again to replace regular numbers. If you would like to remove a number select a cell and tap the X button. This is a JavaScript web application which uses cross-platform mobile-friendly HTML. All modern web browsers like Microsoft Edge, Apple Safari, Google Chrome, Mozilla Firefox and Opera should support it. This game works on just about any type of computing device including Microsoft Windows desktop computers, Apple OSX Mac computers, iOS powered tablets and phones like the iPad and iPhone, laptops like the Google Chromebook, and the many types of mobile phones from manufacturers like Samsung which are powered by Google Android.