I'm sure you're all familiar with the classic logic puzzle Sudoku. A puzzle that has one single solution that can be reached by logical reasoning without any guessing. This site takes things a step further by presenting a range of techniques for solving Sudoku puzzles extremely quickly.
From techniques such as Naked and Pointing Digits to Triplet and Quad techniques it makes for some interesting reading. And more importantly (for this is a Phaser site) it's backed up with a neat playable app built in Phaser that teaches you the methods you need to solve the puzzles in record time.