Puzzle games are all the rage these days. As with all things related to technology, puzzle games have been evolving - and quite rapidly, too. Have you seen the new Alchemy game? Yet even as they continue to change and improve, the classics will always remain, and what greater classic is there than Sudoku?

In case you’ve been living under a rock for the past few decades, Sudoku is a logic-based puzzle game that involves the placement of numbers in certain combinations. It presents you with a 9x9 grid of cells that is broken down further into 3x3 regions. Some of these cells are filled in with certain numbers at the start, thus determining the difficulty.

The goal is to fill in the entire board such that each 3x3 region contains all of the digits from 1 to 9. The catch is that each row and column must also contain every digit from 1 to 9. This means that each digit will appear on the board 9 times: once in each region, once in each row, and once in each column.

It’s extremely easy to play, though hard to master. Fortunately, with Andoku Sudoku, you’ll be able to play this awesome game on the go no matter where you are. Plus, it comes with a number of awesome features you won’t find elsewhere.

The interface for Andoku is extremely intuitive and light. There are no distractions and it does its best to stay out of your way.

When you begin a new game, you’ll be presented with a few options: the style of grid that you want to play, the game mode that you want to play, and the difficulty level of the board. If you want to play a regular game of Sudoku, select “Standard” grid and the “No extra regions” mode.

For the hardcore Sudoku fans out there, Andoku comes equipped with 5 different difficulty levels: Easy, Medium, Challenging, Hard, and Fiendish. As a Sudoku newbie, let me tell you that I was able to beat an Easy game in around 5 minutes. Fiendish was near impossible. I gave up.

By this time, you might be wondering what “Extra Regions” means. X-Sudoku? Hyper-Sudoku? What are these strange but awesome-sounding game modes? We’ll get to that later. Suffice it to say that hardcore Sudoku players who want a real challenge will enjoy what’s coming up.

Here we’ve got a good look at Andoku’s gameplay. The board is easy to read, which is a massive plus. I can’t tell you how many times I’ve played a version of Sudoku only to give up because the interface was clunky. How difficult could it be? Luckily, Andoku hits the nails on the head here.

But Andoku is by no means barebones. It comes with a cell highlighting feature that I found extremely useful. And then there’s Undo/Redo, which isn’t really necessary but useful all the same.

When you’re done, it reports how long it took you to finish the game as well as the average amount of time you spend solving a Sudoku board of that particular setting and difficulty--a great feature for competitive solvers.

Now here is where Andoku really sets itself apart from every other Sudoku game I’ve played. Remember that “Extra Regions” setting from before? This is what it does:

• Squiggly Sudoku: Jumbles up the default 3x3 regions into misshapen squigglies, forcing you to think differently. Each region must still contain only one of each digit from 1 to 9.
• X-Sudoku: Adds an additional constraint to the board such that the diagonals from top-left-to-bottom-right and top-right-to-bottom-left must contain every digit from 1 to 9.
• Hyper-Sudoku: Adds 4 extra 3x3 grids that overlap at the intersection of the default 3x3 grids, requiring you to make sure that those extra regions only contain one of each digit from 1 to 9.
• Percent-Sudoku: A mixture of X-Sudoku and Hyper-Sudoku in that the additional constraints are a single diagonal and two extra 3x3 regions. They overlap the board in the shape of a percentage sign.
• Color-Sudoku: Assigns a color to each individual cell. All of the numbers in cells of a particular color must only contain one of each digit from 1 to 9.

And lastly, Andoku offers some customization of its features. Feel free to change the color theme from Classic to Dark as well as fiddle around with the coloring of the individual 3x3 regions. If some features don't suit you--like the highlighting of the selected digit--then you can turn it off. These are just little things in the grand scheme, but it's great that Andoku lets the user optimize their Sudoku experience.

I don’t know about you, but Andoku Sudoku has really impressed me. I went into it thinking that it couldn’t be all that great; surely the original Sudoku board is all that I need! But after giving it a whirl, I’m convinced that no other Sudoku app on Android is as good as Andoku.

Andoku has a rating of 4.7 on Google Play out of 9,854 reviews. If you love Sudoku, I highly recommend giving it a try. If you don’t, there’s nothing left for me to say except that you’re really missing out!