To coincide with the launch of Properly Killer Sudoku, we’ve just released a brand-new edition of the ever-popular Killer Sudoku Challenge. You can get it right now, completely free, here.
The Challenge has always been a brilliant way to test out your solving skills. Now, with this new edition, it’s also a great way to discover our new Properly Clear Killer Sudoku grids.
We rebuilt our grids from the ground up, putting clarity at the core of the design. We tweaked the target sum numbers, fiddled with the cage boundaries, and subtly shaded the cages themselves, too.
The result is a grid that is effortless to navigate. Cages leap off the page, every one clearly defined and separate from its neighbours. This reduces cognitive load. You might not be consciously aware of it, but your brain doesn’t have to work to figure out where the cages are, and that leaves it free to concentrate on what actually matters: solving the puzzle. Once you’ve tried one of these grids, it’s hard to go back to anything else.
Just like the previous edition, the Challenge includes seven puzzles of increasing difficulty. And because the puzzles have been rated by our unique new Properly Graded system, you’ll find a smoother progression from the simplest to the most infuriatingly difficult.
Our grading system analyses the techniques you’ll be required to use to complete a puzzle. It also looks at things like how quickly you can start getting numbers into the cells – those all important “easy wins”. It takes all of this, mashes it up and gives the puzzle a difficulty score. The score is human-tested, calibrated, and validated by real players (because we love this stuff). So there’ll be no nasty surprises when you start out with puzzle number one (difficulty rating: 0), and equally you’ll know you’re in for a real mental workout when you reach number seven (difficulty: 90).
The new Challenge includes a solving guide with tips and tricks on how to approach Killer Sudoku, in case you’ve never tried it before. There’s also a full copy of our popular Cheat Sheet, should you want to short-cut some mental arithmetic, a skills tracker to monitor your progress, and, naturally, a full set of solutions at the back.
Oh, and did we mention that the whole thing is completely free? We don’t even want your email address! You can download it right now, as a PDF. Just about anything with a screen will open a PDF, so you can print it, or solve on screen with a stylus, finger, or whatever your device supports.
If you love our beautiful new grids and want even more of a challenge, don’t forget to check out Properly Killer Sudoku, where you’ll find 300 puzzles. With just two to each page, there’s plenty of room for notes and sums.