Zen Sudoku (and Sudoku in all its guises) is a deceptively
simply game. It takes place on a board divided into a grid
of 81 squares divided into 9 sets of 9 squares (3x3 subgroups).
The goal is to place one instance of the numbers 1 through
in each column and row, with all of the numbers 1 through
9 also appearing in each of the 9 sets of 9 squares. Each
game begins with some numbers already placed strategically
on the board to help you get started. Easy levels provide
a lot of starting numbers. As you progress to more difficult
levels, there are fewer and fewer starting numbers provided.
As well in the more difficult levels, the few starting numbers
are placed in positions which offer little or no hint for
other number positions.
At all levels of game play, you'll find that there seem to be several
possible numbers that can be placed in most of the empty squares. The
thing is, there's actually only one correct solution for each board.
Zen Sudoku, like most of its competitors, offers a feature called Pencil
Marks which essentially allows you to mark down the possibilities for
each empty square, gradually eliminating the possibilities as you find
more and more correct numbers. But because there are often several incorrect
possibilities for each of the empty squares, it's also possible to play
to a point where you can't make any more moves and end up with unsolved
empty squares. That means you have to backtrack. Zen Sudoku (all good
Sudoku) is challenging and provides terrific exercise for your brain.

**Cons:** Zen Sudoku has all the right things going for it,
but is unfortunately cursed with a visually distracting game
board. The separation grid lines between the nine-squares
are drawn using a low contrast color and we found ourselves
constantly checking to ensure that we were actually estimating
number positions for the correct set of squares. So why didn't
we simply turn off the distracting background graphics? Because
the configuration settings do not allow it. Unlike Numberz,
there's no move checker to determine after a particular move
if the game is still solvable. Purists might recoil at this
(and some purists I know who play Numberz never use the move
checker), but I personally don't find that the feature detracts
from game play. Discipline and patience, when playing Sudoku,
are everything. I think that it's a comparatively small effort
for Deluxeware or Island Labs to tweak the Zen Sudoku game
code and configuration screen so that graphic backgrounds
can be turned off, add more visual contrast to the nine-square
grid, and add a move checker button.

**Pros:** One
of the Sudoku fanatics I know has color acuity issues and,
unexpectedly, that deficiency allowed him to see the Zen
Sudoku nine-square sections quite clearly. He wondered
out loud what all the fuss was about. He loves Zen Sudoku
and we certainly understand why. We just wish we could
play it as enjoyably too, because the game has all the
right functionality. Zen Sudoku responds quickly to taps
and drags, and the number grid pop-up is a clever alternative
to dragging & dropping
a selected number to a square. Just tap & hold a blank
square in any part of the grid and a little sub-grid pops
up containing only available number choices—tap your
selection. The game level and puzzle logic seems to be different
than Numberz, so if you're already used to Numberz you may
find that it takes significantly longer—as long as
several weeks, or even a couple of months—to work your
way up to the Very Hard level in Zen Sudoku. All in all it's
a worthy addition to the Sudoku lineup. Download the trial
version to give it a try.