Sudoku is an addictive numbers game that stimulates the mind. For even the best players, these puzzles require tips and secrets. Just noticing a few patterns in a Sudoku game can be the difference between a solved puzzle or complete frustration.
It may seem obvious, but performing a simple scan over the Sudoku puzzle before beginning can be beneficial. Just looking over the grids will likely uncover a few extra numbers. This creates an immediate advantage as you progress through the rest of the puzzle.
Many advanced Sudoku players will use a pencil to write the number possibilities inside a given square. This helps you keep track of what can and cannot go into the square. As you eliminate possibilities, you can simply erase the number. By doing this, you may also identify singles or hidden singles, which are numbers that can only appear in that square.
Two similar secrets for advanced players are the X-wing and swordfish techniques. If you find two rows that share the same number possibility in the same column, you can eliminate this number as a possibility from other spaces in these columns. The X-wing name likely derives from the pattern made by the crossed out numbers.