How hard can it be to match differently colored squares so that they blend perfectly? Pretty hard, it turns out.

That's the premise behind Blendoku, the game that's a mish-mash of color-blending and sudoku that will challenge you through 475 free levels. It might sound a little odd, but give it a shot,and you're bound to be addicted.

What Do You Mean Sudoku With Colors?

Sudoku is a popular game to mix with – take Drop7 for example, one of last year's most addictive games that mixed Tetris with Sudoku – but Blendoku takes this in a completely different direction. Whereas you would normally have to add up numbers, Blendoku gets rid of the numbers completely, replacing them with colors that need to be blended.

The layout of the game will change as you progress, getting more and more difficult. Above, you can see how the game gets harder from the simple difficulty levels to the medium ones.

At the start, a few of the colors will be placed on the grid, but the rest will be empty. It's then your job to fill in the empty ones so that all the colors perfectly blend into each other. For this, you've really got to know your colors.

You can either drag the pieces to their location, which will result in the line animation shown in the left image above, or you can tap the colored square and then tap where you want it to go, as shown in the right image above. If you can get them all on the first try, you get a Perfect star. If you can get it before the world average, you get a trophy.

The game works in landscape and portrait, but the advert that runs along the top of the screen makes it feel less cramped in portrait. In the bottom right, you get a Solve. Using a Solve provides you with the correct location of one of the squares, but you only get one per day. Naturally, you can buy more via in-app purchases.

But Won't I Get Bored Quickly?

Nope.

While it doesn't have the immersive 3D graphics of Smash Hit, one of my current favorite Android games out there, Blendoku works nicely within its 2D framework by adding smooth touches of color. The black background is accented nicely by beams of light that appear whenever you tap the screen. It's a cool effect that makes the whole game feel much more professionally put together, and it's enough to keep you playing.

With the wide variation in colors and grid shapes, you're never playing the same level twice, and just when you think you'll only do one more level, your mind starts piecing together the next puzzle.

If you get bored of the simple levels, don't worry, this game doesn't require you to beat them to progress. You can just jump all the way up to the hard levels if you're feeling daring.

Plus, there is no shortage of levels available. After you get through the first 150 simple levels, there are four further difficulty levels to get through. If you're willing to pay up, there are 6 more level packs, and buying any of them will also unlock "negative" mode which allows you to play the game through again with inverted colors, essentially doubling the amount of levels.

In-App Purchases And Settings

Each new level pack costs $1.99, and you can get 5 more Solves for $1.99, or 20 Solves for $2.99, or 50 Solves for $4.99. Any of these purchases will also remove the ads from the top of the screen. However, unlike most games, which run the banner ads at the bottom where you're likely to click on them, Blendoku's stay at the top and well out of accidental clicking range.

There's also a Color Blind mode which activates a button for swapping around the color swatches if you're color blind and can't distinguish certain colors. This is a pretty thoughtful addition from the developers.

Blendoku uses sync codes for syncing your progress across devices. Just get the code from one device, enter it on the other, and all your progress will transfer. It's a neat way for keeping your progress without needing an annoying login.

Download it!

You can go ahead and get started with Blendoku either on both Android and iOS, and if you like this, don't forget to check out our lists of the best Android and iPhone games.

Download: Blendoku for iOS / Android (Free)

What do you think of Blendoku? Any other puzzlers out there that deserve a look?