UniSudoku 1.7

Normally reviews of games are the purview of Peter Cohen over on the Game Room Weblog. But Peter isn’t much of a Sudoku fan, so I’ve had the pleasure of using and reviewing David Ross’ UniSudoku 1.7 (   ; $15).

There are plenty of options out there for playing Sudoku on your Mac; a search on VersionTracker yields 38 matches, most of which are computer-based Sudoku games. As a bit of a Sudoku fan myself, I’ve actually tried most of them, but here’s the thing: although there are some that look great, and some that have clever features, very few can replicate, or even come close to replicating, working on a Sudoku puzzle in your Sunday paper or a puzzle book. UniSudoku comes the closest.

UniSudoku offers six puzzle options. You can hand-enter a puzzle you’ve found elsewhere (for example, the newspaper), or you can have the program automatically generate a puzzle at one of five difficulty levels: Very Easy, Easy, Medium, Hard, or Very Hard. (Note that difficulty isn’t necessarily a function of the number of squares initially filled in; rather, how much the initial squares will help you fill in other squares, and what type of analysis will be required to solve the puzzle.)

As you move your mouse cursor over a square, a tiny grid of grayed-out numbers appears; click on a number and it changes color to indicate that it’s a “possible” for that square. Move the cursor out of the square and only the possibles remain. This feature is easy to use and provides useful information without cluttering the interface; it replicates the various notations Sudoku players use while solving puzzles. (If you ever want to get rid of the possibles for the entire board, a simple menu command erases them; another command temporarily hides them if you don’t want to see the clutter.)

To fill in a square, you simply double-click the desired number in this small grid. (You can also use the keyboard to navigate and fill in squares.)

That’s the basic gameplay, but UniSudoku includes a number of useful features for solving puzzles. Some of these offer mainly convenience, while others walk the line between convenience and “help”—you’ll have to decide how much help you want to accept. On the convenience side, one feature lets you highlight all given or solved instances of a particular number; for example, to more easily see where all the sevens are on the board. (The game can also flash a number when you’ve solved all instances of that number.) You can rotate the entire puzzle if you’re better at scanning rows than columns (or just to get a different perspective on the puzzle), and unlimited Undo and Redo are available.

On the “help” side, you can choose to have UniSudoku indicate incorrect answers, and there’s an option to automatically update the possibles for every square. If you turn on the latter option at the beginning of a game, it automatically fills in all the possibilities, leaving you to solve the puzzle. Although this makes for a quicker game, I personally use this feature only after I’ve solved a few squares and done my own possibles-marking. Then, when I solve a square, UniSudoku removes that number from the possibles in squares in the same box, row, or column—something I could easily do myself, but that’s convenient to have done automatically.

Options include custom colors for given numbers, solved numbers, possibles, and highlighting; a puzzle timer; and a sidebar that displays statistics about times and the current puzzle. You can also print puzzles if you want to do them the old-fashioned way.

Finally, there’s one other other thing I like about UniSudoku: that it does “real” Sudoku—at least as I consider it. Many people, including myself, will tell you there are two things that make a genuine Sudoku puzzle that are frequently violated by electronic Sudoku games. First, that you must be able to solve the puzzle without guessing. Logic, even if it’s difficult logic, should always hold the answer; you shouldn’t have to try out a particular solution and then retrace your steps if it doesn’t work. Second, a starting Sudoku board should always be filled symmetrically; that is, boxes across from each other on the board should be mirror images of each other. UniSudoku’s puzzles adhere to both of these guidelines.

The developer claims that the challenge in creating a computer-based Sudoku game is to “keep the flow and simplicity of the pencil and paper version while adding benefits of computer play.” I’d say he’s overcome that challenge and then some: UniSudoku is the best computer-based Sudoku game I’ve tried because it foregoes the fancy visuals of other Sudoku offerings in favor of a puzzle-lover’s clear and clean interface, gets the gameplay right, and adds useful features for actually playing and solving puzzles.