“S’more software”

A Smartphone Sudoku Buying Guide

by David Taylor, Smoresoft, Inc.

Let's face it. There are a lot of Sudoku games out there for your Smartphone. How do you choose the right one?

While there are many flashy advertisements and gimmicky features to grab your attention, you'll want to be sure that the basic game play is solid, or you'll soon regret your purchase as the novelty of the gimmicks wears off.

Even worse, you may be entirely turned off to Sudoku by a poorly designed game, and miss out on the joys of solving a well-made Sudoku!

With this in mind, here is a list of the top 5 items you should consider when buying a Sudoku game and why:

1. Display size

First and foremost, make sure the digits on the grid are easy to read.

If you can't read the digits without getting a pounding headache, it doesn't matter how many features and cool effects are in the game. You're just going to say, "Ouch, my head hurts!", and move on to a less painful activity.

Smartphone screens are already tiny. If your Sudoku game cannot fill the screen with the largest puzzle grid possible on your device, discard it immediately.

2. Digit entry

Playing Sudoku involves entering pencil marks and digits. Lots of them.

Unfortunately, many Sudoku games make this task unnecessarily cumbersome, to the point that it becomes a distraction from the puzzle you're trying to solve.

If you use a keypad, make sure you can enter digits and pencil marks with a single keypress. Trust me, having to switch modes or press multiple keys for every digit entered will put you in a bad mood in a hurry, not to mention spoil your best solving times.

3. Pencil marks

Unless you play only easy grids (and it's likely you'll eventually want to move up), you'll need to keep track of potential candidate values for a cell using pencil marks (aka "candidates").

Pencil marks should be clearly visible on the grid. The size of your screen may determine the type of pencil mark that is most appropriate for your device. A good Sudoku game will support at least three styles of pencil marks:

If your game is capable of displaying more than one style of pencil mark, you'll be able to experiment with the one that suits you best. When you're stuck on a puzzle, it sometimes even helps to switch to a different style to get a fresh look.

4. Auto Pencil Marks

This is one of the nicest benefits of playing Sudoku using a computer instead of pencil and paper.

When you start playing more advanced puzzles, you'll find you often have to painstakingly enter all of the possible candidates for every cell to find your next move. Do this enough times (and make a few mistakes along the way), and you'll really start to wish there was a better way.

After all, looking in the box, row, and column of each cell to mark the legal candidates is more like patiently enduring poke after poke in the eye with a sharp stick than an intellectual challenge.

Fortunately, you can throw away that stick because a good Sudoku game will calculate all of the possibilities for you in the blink of your remaining good eye. You should have the option to calculate the pencil marks at a given point in time (set pencil marks), hide or show the pencil marks at any time, or to simply let the game recalculate them after every move (auto-pencil marks).

It's very important that the game does not modify pencil marks that you've set or cleared manually. Some naïve game implementations simply reset the pencil marks after every move (or after an undo), which puts the pencil marks that you just eliminated using that hard-to-find naked quad right back in play. Now that's downright unneighborly.

5. Backlight

Do I really need to explain how annoying it is when you're concentrating intently on a diabolical puzzle and the screen keeps going blank?

Well, it's not as annoying as forgetting that you turned off the backlight timeout on your phone, put it in your pocket, and later found out that the battery was dead just when you needed to call your broker to cash in on your hot Enron shares and now it's too late, your stock has crashed, you're penniless, and your dreams of retiring to travel the world have been dashed. So much for your life of leisure.

Needless to say, you should look for an in-game option to keep the backlight on while you're concentrating, and let it turn off normally when you're done playing so your phone won't be dead when you need to make that 9-1-1 call. It could literally save your life.


There are many other great features to have in a Sudoku game, none of which involve playing the game with colored fruits or sports equipment.

To name a few:

However, without the aforementioned basic functionality, these features will go unused when you throw the game away in frustration after a few days.

A game that excels in the areas covered in this guide should provide you with many enjoyable hours of game play.

Happy solving!

Play Sudoku on your Smartphone